Physical science (1)

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PHYSICAL
SCIENCE
QUARTER 1
LEARNING ACTIVITY SHEE

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Learning Activity Sheet in EARTH SCIENCE
(Grade 12)
Copyright © 2020
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NOTE: Practice personal hygiene protocols at all times
Table of Contents
Compentency Code
Page
number
Give evidence for and describe the formation of
heavier elements during star formation ad
evoution S11/12PS-IIIa-2 1 - 20
Explain how the concept of atomic number led
to the synthesis of new elements in the
laboratory S11/12PS-IIIb-11 21 – 33
Determine if a molecule is polar or non-polar
given its structure S11/12PS-IIIc-15 34 – 52
Relate the polarity of a molecule to its
properties S11/12PS-IIIc-16 53 – 69
Describe the general types of intermolecular
forces
S11/12PS-IIIc-d-
17 70 - 79
Explain the effect of intermolecular forces on
the properties of substances
S11/12PS-IIId-e-
19 80 - 100
Explain how the structures of biological
macromolecules such as carbohydrates, lipids,
nucleic acid, and proteins determine their
properties and functions S11/12PS-IIIe-22 100 - 131
Use simple collision theory to explain the
effects of concentrate temperature, and
particles size on the rate of reaction S11/12PS-IIIf-23 132 - 145
Define catalyst and describe how it affects
reaction rate S11/12PS-IIIf-24 146 - 154
Determine the limiting reactant in a reaction
and calculate the amount of product formed S11/12PS-IIIh-27 155 - 174
Describe how energy is harnessed from
different sources:
A. Fossil fuels
B. Biogas
C. Geothermal
D. Hydrothermal
E. Batteries
F. Solar cells
G. Biomass
S11/12PS-IIIi-29 175 - 194

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From product labels, identify the active
ingredient(s) of cleaning products used at home S11/12PS-IIIi-j-31 195 - 209
Give the use of the other ingredients in cleaning
agents S11/12PS-IIIi-j-32 210 - 225

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PHYSICAL SCIENCE
Name: ________________________________________Grade Level: _________
Date: __________________________________________Score:______________
LEARNING ACTIVITY SHEET
INTRODUCTION TO STELLAR EVOLUTION, THEIR SOURCE OF
ENERGY AND THE LIFE CYCLE OF STARS
Background Information for the Learners (BIL)
The Big Bang and the origin of the universe
This diagram shows the
expansion of the universe shortly
after the big bang. The time
increases from left to right, with
important events identified on the
image. The events are represented
by stacked graphs on a time-
continuum. Two of the most
important events with respect to this
lesson are the first stars (~ 400
Million years ago) and the
subsequent development of galaxies and planets.
Under the current cosmological model for the beginning of the Universe, the
“Big Bang” occurred ~13.8 billion years ago. Under this model, the Universe was
extremely hot and dense and an “explosion” caused it to begin expanding rapidly.
After the initial expansion, it then began to cool allowing the energy and matter to
condense to form subatomic particles, such as protons, neutrons and electrons. A few
thousand years later, the first atoms (with stable atomic nuclei) formed. These
“primordial elements” consisted of hydrogen and helium, with some lithium. These
elements later condensed under the force of gravity to form stars, which then formed
https://en.wikipedia.org/wiki/Big_Bang

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heavier elements, either through fusion or during supernovae the first stars began
forming about 400 million years after the Big Bang.
The Hertzsprung-Russel Diagram (HR Diagram) shows the relationship
between the absolute magnitude (luminosity / brightness) of stars and their
temperatures. The brightest stars are toward the top of the diagram while the hottest
stars are on the left of the diagram. The main band that stretches across the diagram
(bottom right to top left) consists of the Main Sequence Stars.
These main sequence stars are in hydrostatic equilibrium, meaning that their
inward gravitational pressure is balanced by outward thermal pressure (generated by
the fusion within the hot core). The main sequence represents the major hydrogen-
burning phase of a star’s lifetime. A general rule is that the larger a star, the shorter its
life span along the main sequence branch.
Following the hydrogen-burning phase, more massive stars can evolve along
the red-giant-branch (RGB) or asymptotic-giant-branch (AGB) stars. These are
represented by the branch in the top right. RGB stars continue to fuse hydrogen in
their cores while AGB stars begin to burn heavier elements such as carbon and
https://en.wikipedia.org/wiki/Hertzsprung–Russell_diagram

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oxygen. While these stars will not be discussed in explicit detail, they are important to
the formation of elements through stellar nucleosynthesis.
What is Stellar Nucleosynthesis?
Elements heavier than beryllium are formed through Stellar nucleosynthesis –
is the process by which elements are formed within stars. The abundances of these
elements change as the stars evolve.
Learning Competency:
Give evidence for and describe the formation of heavier elements during star formation
and evolution (S11/12PS-IIIa-2)
Activity 1: Find Me
...refer to Hertzsprung-Russel Diagram
Questions:
1. What colors are the hottest stars? _________________
2. What colors are the coolest stars? _________________
3. Which stars are the smallest? __________________
4. Which stars are the largest? __________________
5. Which stars are the brightest? __________________
6. Which stars are the dimmest? __________________
7. What classification of star is the hottest? ____________
8. What classification of star is the coolest? ____________
9. What classification is our Sun? __________________
10.What color is our Sun? __________________
11.Compared to other stars what is the Suns temperature?
12.Where does the Sun fit in this diagram?

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Key Points on the Evolution of Stars
There are different evolutionary paths for low-mass stars (like the Sun) and high-
mass stars, but they both begin with growth along the Main Sequence.
Star-forming (stellar) nebula condenses to form proto-stars, which then
condense further to form full-fledged stars. At this point, the core reaches 10 million
Kelvin, which initiates hydrogen fusion, thereby generating energy for the star. The
hydrogen fusion maintains the star through hydrostatic equilibrium (with external
thermal pressure counteracting inward gravitational collapse). This star is currently
on the main sequence, but after the core uses up its hydrogen supply for fusion, the
fate of a star will differ and depends on the size of the star.
...refer to Hertzsprung-Russel Diagram
13. What is the color of the hottest stars?
14.Which classification of stars has the most energy?
a. How is a star’s temperature related to its energy?
b. How is a star’s magnitude related to its energy?
c. How is a star’s luminosity related to its energy?
d. Hypothesize what classifications of stars are at the
beginning of their life cycle and which are at the end of their
life cycle?

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EVIDENCES OF FORMATION OF HEAVIER ELEMENTS THAN BERYLLIUM
In the evolution of stars, they grow and exhaust their fuel, changing to a different
source of energy (i.e. a different element). For a typical main sequence star, the
stars begin producing energy from hydrogen burning (proton-proton fusion).
Eventually, the supply of hydrogen begins to decrease and finally the core is entirely
depleted and consists only of helium.
As the main sequence star glows, hydrogen in its core is converted into helium
by nuclear fusion. When the hydrogen supply in the core begins to run out, and the
star is no longer generating heat by nuclear fusion, the core becomes unstable and
contracts. The outer shell of the star, which is still mostly hydrogen, starts to expand.
As it expands, it cools and glows red. The star has now reached the red giant phase.
It is red because it is cooler than it was in the main sequence star stage and it is a
giant because the outer shell has expanded outward. In the core of the red giant,
helium fuses into carbon. All stars evolve the same way up to the red giant phase. The
The outward push from
thermal pressure
The inward
push from
gravity
The pressure is
generated from
the thermal
energy from
nuclear fusion
in the core
http://woodahl.physics.iupui.edu/Astro105/

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amount of mass a star has determines which of the following life cycle paths it will take
from there.
This results in an expansion of a large, outer-atmosphere of the star, resulting
in a large radius and a low surface temperature. This is a characteristic Red Giant. It
is a luminous giant star with low to intermediate mass (0.3-8 solar masses), and a
relatively low density (because of the expanded radius).
Gravity again squeezes the star. In a low-mass star, there is not enough mass
for a carbon fusion to occur. The star’s fuel is depleted, and overtime, the outer
material of the star is blown off into space. The only thing that remains is hot and inert
carbon core. The star becomes a white dwarf.
A large star (larger than our Sun) that is massive enough to continue past He
burning to carbon, oxygen and silicon burning will eventually result in a layered
structure (like an onion). Each element begins to burn, the lighter element moves into
a shell around it. Therefore, when the star begins to burn carbon, there would be a
shell of helium-burning, surrounded by another shell of hydrogen-burning. This
continues through to silicon-burning, which deposits iron in the core and continues in
a small shell around it.
During these different stages of fusion, the star is able to balance the inward
force of gravity with outward thermal pressure. This is because of the energy and heat
generated from the fusion in the shells. When fusion stops, however, and the core
consist of Fe, the star can no longer generate energy from fusion. This is because Fe
has a high binding energy and its fusion is an energy-consuming process. Therefore,
the star can no longer balance the inward force of gravity with an outward thermal
pressure; without the generation of heat and energy, the star will collapse and then
explode into a supernova type II.
Hydrogen burning describes the process in which the fusion of protons
ultimately leads to the formation of a Helium-4 nucleus (also known as an alpha
particle).

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The proton-proton chain reaction consists of three steps.
1. In the first step, two protons fuse at very high temperatures to create a Deuterium
nucleus (in this step, one of the protons actually becomes a neutron, through beta-
plus radioactive decay). Deuterium has an atomic number of 1 and an atomic mass
of 2 and therefore is a heavy isotope of hydrogen.
2. In the second step, the deuterium nucleus fuses with a proton to form a Helium-3
nucleus, which consists of 2 protons and 1 neutron.
3. In the third step, two Helium-3 nuclei fuse together. This is an energetic reaction
that results in the release of 2 protons. The final product is a Helium-4 nucleus, with
2 protons and 2 neutrons; this is also referred to as the alpha particle.
The alpha particle, or Helium-4 nucleus, consists of 2 protons and 2
neutrons. It has an atomic number of 2 and an atomic mass of 4 (sum or protons
and neutrons).
In stars, it is produced during the third step of hydrogen burning (or proton-
proton chain reaction). It is an important particle, because it is not only the end-point
of hydrogen burning, but can produce larger, heavier nuclei during the alpha process.
https://en.wikipedia.org/wiki/Proton–
proton_chain_reaction

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The alpha process (or alpha fusion) is a method by which stars convert helium
nuclei (alpha particles) into heavier elements. Because of the number of protons
and neutrons in an alpha particle, the heavier elements produced by the alpha process
have an even number of protons and neutrons. Elements with odd atomic numbers
can subsequently produce by radioactive decay or from other reactions, such as
during a supernova.
Triple-Alpha Process: Step 1
In the first step, two helium nuclei
combine to form a beryllium
nucleus. There is a conservation of
atomic mass and the resulting
nucleus has 4 protons and 4
neutrons (with an atomic number of
8).
Triple-Alpha Process: Step 2
Here, the beryllium nucleus
formed in the previous step fuses
with an additional alpha particle,
resulting in a carbon nucleus. The
beryllium-8 produced from the
previous reaction is highly unstable
and therefore either decays rapidly
or reacts with an alpha particle to
produce carbon.
It should be noted that not all the
products of fusion in stars are
stable. In this example, the
formation of beryllium-8 is important
for the formation of carbon-12, but
the majority of beryllium actually
formed during the Big Bang (this is
possible because it is such a light
element).
https://en.wikipedia.org/wiki/Proton–proton_chain_reaction

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Chain of Alpha Processes
https://slideplayer.com/slide/12355862/
The general process, in which an alpha particle is added to a nucleus results in
a chain of reactions. This set of reactions is also known as the alpha ladder. It can
form all the even elements from beryllium to iron. The reactions proceed at a very low
rate and do not contribute significantly to the energy production in stars, but are
important for the generation of the elements.
Activity 2: Proton-Proton Fusion Activity!
The students will identify the steps that are involved in the nuclear fusion, and
model them using cotton balls and glue. The purpose of re-creating the diagrams
presented in class is to provide them with a tangible grasp of the material.
Main Theory:
A hydrogen atom has the most basic nucleus in the universe. It is made
up of one proton. In the core of a star the temperature is high enough
(10,000,000K) to start nuclear fusion. Nuclear fusion is the process of
combining nuclei to form new, larger nucleus element. This activity will
go step by step through the process of converting Hydrogen into Helium.

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Part 1
Theory
In the first step, 2 protons combine. In doing so one of the protons will convert
into a neutron by losing a positron (positive electron) and a neutrino; this is also known
as beta decay. Beta decay occurs when, in a nucleus with too many protons or too
many neutrons, one of the protons or neutrons is transformed into the other.
This changes one of the protons (positive charge) into a neutron (neutral charge) and
allows the two particles to combine.
Directions:
1. Come up to the front and collect two white cotton balls and a glue
stick (These white cotton balls represent two protons, so one
hydrogen nucleus each)
2. Glue the cotton balls down to in the proper location, with each proton
representing one hydrogen nucleus.
3. Collect 2 new cotton balls, one white (proton) and one red (neutron).
Glue these down in the correct location, to represent a deuterium
nucleus (the product of the reaction).
4. Let the cotton balls dry and glue them into the proper location.
Part 2
Theory
In the second step, a proton combines with a deuterium nucleus
(produced in step one). This new nucleus will now have 2 protons and
1 neutron, and represent a Helium-3 nucleus. Note that the hydrogen
nuclei combined to form a new element, helium.
Directions:
1. Collect 4 white cotton balls (protons) and 2 red cotton balls (neutrons)
2. On the given worksheet glue the white and red cotton balls in the
proper locations, with the two reacting species consisting of hydrogen
(1 proton) and deuterium (one proton, one neutron). After they
combine, their product can be represented by 2 protons and 1
neutron (Helium-3 nucleus).
Part 3

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Theory
The nucleus from step 2 is a Helium-3 nuclei. In step 3 two Helium-3
nuclei will combine to form a Helium-4 nucleus and release 2 protons
(i.e. 2 hydrogen nuclei). The resulting Helium-4 nucleus is also referred
to as an alpha particle.
Directions:
1. Collect 8 white cotton balls (protons) and 4 red cotton balls (neutrons)
2. On the given worksheet, glue the white and red cotton balls in the
proper locations. The two products should be Helium-3 nuclei, with
2 protons and 1 neutron each (therefore 2 white and 1 red cotton
balls). The product of this reaction is a Helium 4 nucleus (2 protons
and 2 neutrons; 2 white, 2 red). The two protons that are release by
this reaction can be represented by the remaining 2 white cotton balls
(these are individual hydrogen nuclei).
Activity 3: Alpha Fusion Activity!
Objective:
Students understand how heavier elements (Be to Fe) are formed and make
models that show the nuclei of these elements forming.
Directions:
Part 1
1. Get a package of white cotton balls and a package of red cotton balls
2. Each WHITE cotton ball represents 1 PROTON
3. Each RED cotton ball represents 1 NEUTRON
4. Make an Alpha particle by gluing 2 protons (White) and 2 neutrons (Red)
together.
5. After combining, count the total number of protons (white) to find the
atomic number (the number of protons found in the nucleus of every atom
of an element) the new nuclei your created and write it down on your
periodic table. What is this nuclei’s atomic number?

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6. Now count the number of neutrons (red) and ADD that to the number of
protons (white) to find the atomic mass, write it down on your periodic
table. What is this nuclei’s atomic mass?
7. What element has a nucleus like this?
8. On your blank periodic table write in the information in the proper location.
9. Make a second Alpha particle and glue it to the first Alpha particle.
10.What is this nuclei’s atomic number? What is this nuclei’s atomic mass?
What element’s nucleus is this?
11.On your blank periodic table write in the information in the proper location.
12.Make another Alpha particle and glue it to the nucleus
13.What is this nuclei’s atomic number? What is this nuclei’s atomic mass?
What element’s nucleus is this?
14.On your blank periodic table write in the information in the proper location.
15.Repeat steps 13, 14 and 15 until you have an Iron nucleus.
16.What one factor ultimately organizes the elements on the periodic table?
Part 2
1. Look at your periodic table. Are there elements missing between He and
Fe?
Based on the trend that we have been working with, fill in the blank atomic numbers
and atomic masses for the missing elements between He and Fe.
TRY TO THINK ON THIS:
“WE ARE ALL MADE UP OF STARS”
-
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___________________________________________________.

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Activity 4: Plot Me!!
Answer the following questions:
Purpose: Some combinations of neutrons and protons form isotopes
that are not stable and will decay or break apart. This lesson shows
how to predict the proper ratio of protons to neutrons to form stable
isotopes. In nature we find that stable isotopes have an ideal ratio of
protons to neutrons. When charted on a graph (protons vs. neutrons)
we see that stability lies in an area called the band of stability.
Plot the following isotopes on the graph.
Directions: Atomic number and atomic mass is given but the graph has
Neutron on the x-axis and Atomic number on the Y-axis. So the
students must find first the number of neutrons from the given mass
number and atomic number to be plotted in the graph.
24
12Mg 135
60Nd 39
19K 81
35Br 114
44Ru 34
19K
http://www.science.uottawa.ca/eih/ch1/Image4.gif

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1. What does the entire area on the graph represent?
2. What does the black area represent? What is it called?
3. What does the straight line represent?
4. Which elements where charted outside the grey area? What would it indicate
about those elements?
5. There are two K’s (potassium) atoms on the graph. What is it called there are
two atoms of the same element with different atomic masses? What on the
subatomic level, is different between the two atoms?
6. Do all stable atoms have the same number of protons and neutrons?
For more insights visit the link:
https://www.csus.edu/indiv/t/taylorc/SIRC_March22_2011.pdf
Assessment
MULTIPLE CHOICE: Encircle the letter of the correct answer.
1. Which of the following best describes Stellar Nucleosynthesis?
a. a hot cloud of gas where energy is distributed evenly all throughout
b. the formation of atomic nuclei through the combination of hadrons during the
Big Bang
c. the birth of elementary particles in the beginning of time
d. the creation of chemical elements by nuclear reactions within stars.
2. Which of the following is the Heaviest Element?
a. Helium b. Iron c. Carbon d. Silicon
3. What phenomena lead to the formation of Heavy Elements?
a. Cosmic Ray Collisions c. Big Bang
b. Supernovae d. Stellar nucleosynthesis
4. Which of the following is NOT true: Isotopes of the same element ________.
a. have the same number of Neutrons
b. have the same atomic number, but different atomic weights
c. have different number of Neutrons, but the same number of Protons
d. contain the same number of electrons
5. Deuterium and Tritium are isotopes of _____.
a. Hydrogen b. Helium c. Lithium d. Beryllium

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6. All of the Deuterium in our galaxy was formed _____?
a. during the Big Bang c. in fusion reactors of the Earth
b. in Supernovae d. in cosmic ray collisions
7. Which was believed to have produced most Helium in the Universe?
a. red giants b. supernovae c. Big Bang d. main sequence stars
8. Which of the following processes is likely to generate the heaviest element?
a. CNO cycle c. triple-alpha process
b. r-process d. Big Bang nucleosynthesis
9. Lithium and Beryllium are both light elements and are believed to have been
produced in trace amounts during Big Bang. These elements, however, have a
relatively short half-life and could not have survived to the present. If so, where can
present-time Lithium and Beryllium in the universe have come from?
a. emitted during supernova explosions c. upon cosmic ray collisions
b. produced during stellar evolutions d. a by-product of the birth of a star
10. What isotope is formed in the diagram below?
a. Helium-8
b. Lithium-8
c. Beryllium-8
d. Oxygen
11. Which of these is a portion of the electromagnetic spectrum that can go through
the Earth’s atmosphere?
a. X-ray `light’ b. Ultraviolet light c. Gamma-ray light’ d. Visible-wavelength light
12. In what part of the Hertzsprung-Russell diagram would you find the brightest,
hottest main-sequence stars?
a. The upper-left part of the diagram
b. Along the right-hand edge of the diagram
c. The lower-right part of the diagram
d. Along the lower edge of the diagram
13. What is the Sun made of?
a. Mostly oxygen, with a small amount of hydrogen and helium.
b. Mostly hydrogen, with a little helium, and a very small proportion of heavier
elements.
c. Mostly helium, with the rest being mostly various heavy elements, and a very
small proportion of hydrogen.
d. Mostly iron, similar to the hot iron core of the Earth, with a little bit of helium
and some heavier elements.
14. Which of the following processes is likely to generate the heaviest element?
a. CNO cycle c. triple-alpha process
??

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b. r-process d. Big Bang nucleosynthesis
15. Which of the following reactions is not a part of the alpha ladder?
a. 24
12Mg + 4
2He ---→ 28
14Si c. 36
18Ar + 4
2He ---→ 40
20Ca
b. 31
15P + 4
2He ---→ 35
17Cl d. 44
22Ti + 4
2He ---→ 48
24Cr
16. If an element is used up by a star in fusion, it is sometimes called “burning”, even
though no actual combustion occurs. Which of the following processes is likely to
involve “carbon burning”?
a. alpha ladder c. triple-alpha process
b. CNO cycle d. s-process
7-10. Modified True or False: If the statement is true, write True. Otherwise, replace
the underlined portion with the correct word or phrase.
__________________ a. A star gets lighter as time goes on.
__________________ b. Most of the heaviest elements were formed in main-
sequence stars.
__________________ c. The heavy elements in a star are found in its core.
__________________ d. In stellar nucleosynthesis, heavier elements are formed
from combining lighter ones.
Reflection
1. I learned that __________________________________________________
_____________________________________________________________
_______________________________________________________
2. I enjoyed most on ______________________________________________
_____________________________________________________________
_________________________________________________
3. I want to learn more on __________________________________________
_____________________________________________________________
_________________________________________________
References:
K to 12 Curriculum Guide, page 1of 17

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https://www.coursehero.com/file/52900814/Lesson-2-Formation-of-Heavier-Elementspptx/
https://earthref.org/SCC/lessons/2012/nucleosynthesis/
http://en.wikipedia.org/wiki/Electromagnetic_spectrum
http://en.wikipedia.org/wiki/Hertzsprung%E2%80%93Russell_diagram
http://upload.wikimedia.org/wikipedia/commons/6/6b/HRDiagram.png
Bigbang: http://en.wikipedia.org/wiki/Big_Bang
Redshift: http://en.wikipedia.org/wiki/Redshift
Stellar Evolution: http://en.wikipedia.org/wiki/Stellar_evolution
Supergiant: http://en.wikipedia.org/wiki/Supergiant
Supernova: http://en.wikipedia.org/wiki/Supernova
Wolf-Rayet Star: http://en.wikipedia.org/wiki/Wolf%E2%80%93Rayet_star
Stars (NASA): http://imagine.gsfc.nasa.gov/docs/science/know_l2/stars.html
Main Sequence Stars: http://en.wikipedia.org/wiki/Main_sequence
Hydrogen Burning: http://en.wikipedia.org/wiki/Hydrogen_burning#Hydrogen_burning
Proton-proton chain reaction:
http://en.wikipedia.org/wiki/Proton%E2%80%93proton_chain_reaction
Alpha Process: http://en.wikipedia.org/wiki/Alpha_process
Stable Nuclide: http://en.wikipedia.org/wiki/Stable_nuclide
Radioactive Decay: http://en.wikipedia.org/wiki/Radioactive_decay
Answer Key
Activity 1.Find Me!

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Questions:
1. What color are the hottest stars? Blue
2. What color are the coolest stars? Red
3. Which stars are the smallest? White Dwarfs
4. Which stars are the largest? Supergiants
5. Which stars are the brightest? Blue (main-sequence or supergiants)
6. Which stars are the dimmest? White Dwarfs
7. What classification of star is the hottest? Blue Supergiants
8. What classification of star is the coolest? Red (main-sequence or giants)
9. What classification is our Sun? Main Sequence Star
10. What color is our Sun? Yellow
11. Compared to other stars what is the Suns temp? Average (~5000 K)
12. Where does the Sun fit in this diagram? Yellow, along main-sequence
13. What is the color of the hottest stars? Blue and White
14. Which classification of star has the most energy? Blue and White (also, hottest)
a. How is a star’s temperature related to its energy?
The hotter the star, the more energy it has
b. How is a star’s magnitude related to its energy?
Along the main sequence, stars of greater magnitude are hotter (have more
energy)
c. How is a star’s luminosity related to its energy?
For main-sequence stars, the luminosity increases with temperature. For the
giants and super-giants, large (high magnitude) and luminous stars are actually
quite cool.
d. Hypothesize what classification of stars are at the beginning of their life cycle
and which are at the end of their life cycle?
Hotter stars are younger, cooler stars are older. Giants and super-giants are
dying. White dwarfs are also at the end of a life cycle. The main-sequence
stars show a strong relation between temperature (energy) and magnitude and
brightness—the hotter ones of these are younger.
Activity 4. Plot Me
Answer the following questions:
1. What does the entire area on the graph represent?
It represents all the possible nuclides that can form, including those that will
decay because they are unstable.
2. What does the black area represent? What is it called?
It is the “valley of stability” and represents all the stable nuclides that can exist.
3. What does the straight line represent?
It has a slope of one and shows the expected trend for atoms with the same
number of neutrons and protons in their nuclei.
4. Which elements where charted outside the grey area? What would it indicate
about those elements?

19
All nuclides that cannot form, because they are never unstable
5. There are two K’s (potassium) atoms on the graph. What is it called there are
two atoms of the same element with different atomic masses? What on the
subatomic level, is different between the two atoms?
They are called isotopes. They have a different number of neutrons in their
nuclei, but the number of protons is the same.
6. Do all stable atoms have the same number of protons and neutrons?
No, as atoms get larger, they typically have more neutrons than protons
Assessment
TRY TO THINK ON THIS!:
“The idea that “We are all made of stars” is true, because the formation
of the elements occurs in stars and supernovae. These atoms then become the
building blocks of planets and also the life that has come to evolve on Earth. “
Prepared by:
JOLLY MAR D. CASTANEDA
Baggao National Agricultural School-Sta Margarita Annex
PHYSICAL SCIENCE
Name: ____________________________ Grade Level: _________
Date: _____________________________ Score: ______________
1.D
2.B
3.D
4.C
5.A
6.A
7.C
8.B
9.A
10.C
11.B
12.A
13.B
14.B
15.B
16.A
17.HEAVIER
18.SUPERNOVA
19.TRUE
20.TRUE

20
SYNTHESIS OF NEW ELEMENTS IN THE LABORATORY
Chemists within the 19th
century generally approves about what particles
consisted matter and agreed that matter is made of atoms. However, they are not
familiar about the structure of the atoms.
The information about the known elements gave them encouragement to
arrange the elements in a table.
An element is a substance that cannot be broken down into simpler one. Most
known chemical elements are found to occur on Earth naturally. All elements are all
represented by their atomic number, the number of protons in their nucleus. The
natural elements start with hydrogen (1) and end with californium (98).
But it doesn't stop there. Scientists have created 20 other synthetic elements.
Those start with einsteinium —99. You could also consider atomic numbers 95–98
synthetic elements because they’re almost exclusively man-made that results to a total
of 24 synthetic elements discovered. These elements are generally used to fuel
chemical reactors, and these could also be used for detectors and
spectrophotometers. Some are applicable in pharmaceutical industries.
Source: https://en.wikipedia.org/wiki/Synthetic_element
Naturally - Occurring
and Synthetic Elements

21
The table shows the naturally-occurring and synthetic elements. A synthetic
element is one of 24 chemical elements that do not occur naturally on Earth: they have
been created by human manipulation of fundamental particles in a nuclear reactor,
a particle accelerator, or the explosion of an atomic bomb; thus, they are called
"synthetic", "artificial", or "man-made". The synthetic elements are those with atomic
numbers 95–118, as shown in purple on the accompanying periodic table and the rest
are the naturally-occurring elements.
Different elements have different number of protons. Atomic number is equal to
number of protons. All atoms of a given element have the same number of protons but
may have different number of neutrons and atoms of the same element with different
number of neutrons are called isotopes.
Source: http://terpconnect.umd.edu/~wbreslyn/chemistry/isotopes/isotopes-of-hydrogen.html
Discoveries through Nuclear Reactions
Radioactivity is a spontaneous process wherein the nucleus of an unstable
atom disintegrates while releasing radiation and losing energy. It is also called
radioactive decay or nuclear decay. Antoine-Henri Becquerel discovered
radioactivity in 1896. Using the concept of radioactivity, Ernest Rutherford and
Frederick Soddy discovered isotopes in 1914.
In 1919, Rutherford discovered that when a nitrogen nucleus was bombarded
with alpha particles from radium, an oxygen nucleus and a proton were produced.
In 1934, Irene Joliot-Curie and her husband Frederic Joliot discovered that
when an aluminum nucleus was bombarded with alpha particles, a phosphorous
nucleus and a neutron can be produced.

22
Glenn Theodore Seaborg was an American chemist whose contribution in the
synthesis, discovery and study of ten transuranium elements earned him a share of
the 1951 Nobel Prize/honor in Chemistry.
Seaborg was the head or co-discoverer of ten
elements: plutonium, americium, curium, berkelium, californium, einsteinium, fermiu
m, mendelevium, nobelium and seaborgium. According to him, Uranium or plutonium
are being bombarded with neutrons in nuclear reactors. The first production is in 1944.
NUCLEAR REACTION
Nuclear Reaction a term implied that causes a nuclide to change by
bombarding it with energetic particle. It involves a heavy target nucleus and a light
bombarding particle. It can produce a heavier product nucleus and emits a very high
electromagnetic energy. Nuclear reactions may increase or decrease the number of
protons of an atom, thus, producing new elements or isotopes.
SYNTHETIC ELEMENTS
A term for chemical element that does not occur naturally on Earth. It can only
be created artificially, and it is radioactive and decay rapidly into lighter elements. It
only occurs on Earth as the product of atomic bombs or experiments. Scientist
discovered that a nucleus with too many or too few neutrons compared to its protons
is radioactive. Radioactive materials are very unstable. Technetium with an atomic
number of 43 is the first synthetic element that is artificially produced. It was produced
by E. Segre and C. Perrier in 1937 by bombarding molybdenum nuclei with deuterium.
In 1940, neptunium is produced by bombarding uranium atoms with neutrons. Since
then, elements with atomic numbers 95 to 118 have been synthesized.
Explain how the concept of atomic number led to the synthesis of new elements in the
laboratory (S11/12PS-IIIb-11)
Activity 1: Natural or Synthetic?

23
Material: Paper and pen
Periodic Table of Elements
Source: https://www.slideshare.net/JhayGonzales/synthesis-of-the-new-elements-in-the-laboratory
Procedure: Identify whether the given element is natural or synthetic.
Element Natural/Synthetic
1. Fermium
2. Chromium
3. Curium
4. Nobelium
5. Helium
6. Bohrium
7. Calcium
8. Cadmium

24
9. Copernicium
10. Americium
Q1. What is the difference between natural and synthetic elements?
______________________________________________________________
______________________________________________________________
Activity 2: Identify Me
Materials: Activity notebook/pen
Procedure: Identify what is ask in the given statement below. Write your answer on
the space provided for.
__________ 1. A substance that cannot be broken down into simpler one.
__________ 2. These are the atoms with the same number of protons but
with different number of neutrons.
___________ 3. It is the subatomic particle that disintegrates in the
radioactive decay.
___________ 4. The discovery of ________ led to the discovery of isotopes.
___________ 5. It is the first synthetic element produced.
___________ 6. It is the subatomic particle that determines the atomic
number of an element.
___________ 7. It occurs on Earth as the product of atomic bombs or
experiments
___________ 8 - 10. Synthetic elements are artificially produced through the
process of ________.
Activity 3: My Discovery
Direction: Match column A to column B. This is all about the contributions of the
different scientist to the synthesis of new elements in the laboratory.
COLUMN A
1. Ernest Rutherford
2. Frederick Soddy
3. Antoine-Henri
Becquerel
COLUMN B
a. Discovered that when an aluminum nucleus
was bombarded with alpha particles, a
phosphorous nucleus and a neutron produced.
b. He was the first to produce oxygen nuclei and
protons by bombarding nitrogen nuclei with alpha
particle.

25
Activity 4: Research on Me!
Materials: Reading materials/books
Activity notebook/pen
Procedure: Research on how the given discovered/synthesized elements are
produced in the universe.
Put your answer here.
1. Curium
2. Berkelium
3. Californium
4. Mendelevium
5. Nobelium
6. Lawrencium
7. Dubnium
8. Copernicium
9. Hassium

26
Activity 5: Think About It!
Direction: Explain briefly the following questions below.
1. What is the contribution of atomic number in synthesizing new elements?
___________________________________________________________________
___________________________________________________________________
____________________________________________________
2. How are elements synthesized in the laboratory?
___________________________________________________________________
___________________________________________________________________
____________________________________________________
3. How many elements are man-made? naturally occurring?
___________________________________________________________________
___________________________________________________________________
____________________________________________________
4. What are the common characteristics of all synthetic elements?
___________________________________________________________________
___________________________________________________________________
____________________________________________________
5. What are the uses of synthetic element?

27
___________________________________________________________________
___________________________________________________________________
____________________________________________________
REFLECTION:
1. I learned that _________________________________________________
___________________________________________________________________
_________________________________________________________
2. I enjoyed most on ______________________________________________
___________________________________________________________________
_________________________________________________________
___________________________________________________________________
_________________________________________________________
References:
slideshare.net/JhayGonzales/synthesis-of-the-new-elements-in-the-laboratory
www.slideshare.net>bRoKendaRkaNgeI03>6-concept-of-atomic-no
https://www.angelo.edu/faculty/kboudrea/periodic/physical_natural.htm
https://www.vox.com/2014/5/8/5684538/new-chemical-element-117
www.ucoclick.org
https://en.wikipedia.org/wiki/Glenn_T._Seaborg
https://www.quora.com/How-does-the-idea-of-an-atomic-number-lead-to-
synthesizing-new-elements
https://en.wikipedia.org/wiki/Synthetic_element

28
ANSWER KEY
Activity 1: NATURAL OR SYNTHETIC?
Element Natural/Synthetic
1. Fermium Synthetic
2. Chromium Natural
3. Curium Synthetic
4. Nobelium Synthetic
5. Helium Natural
6. Bohrium Synthetic
7. Calcium Natural

29
8. Cadmium Natural
9. Copernicium Synthetic
10. Americium Synthetic
Q1. What is the difference between natural and synthetic elements?
Natural elements are found naturally occurring in the universe while synthetic
elements do not occur naturally, it has to be synthesized or made by humans to
form that element.
Activity 2: IDENTIFY ME
Element 1. A substance that cannot be broken down into simpler
one.
Neutron____ 2. These are the atoms with the same number of protons but
with different number of neutrons.
Nucleus____ 3. It is the subatomic particle that disintegrates in the
radioactive decay.
Radioactivity 4. The discovery of ________ led to the discovery of isotopes.
Technetium_ 5. It is the first synthetic element produced.
Proton __ 6. It is the subatomic particle that determines the atomic number
of an element.
Synthetic elements 7. It occurs on Earth as the product of atomic bombs or
experiments
8 - 10. Synthetic elements are artificially produced through the process
of _________
8. Radioactive decay
9. Bombardment of Nucleus
10. Nuclear reaction
Activity 3: MY DISCOVERY
1. B
2. D
3. E

30
4. A
5. C
Activity 4: RESEARCH ON ME!
Put your answer here!
1. Curium (Cm) - produced by bombarding uranium or plutonium with
neutrons in nuclear reactors.
2. Berkelium (Bk) - produced by bombarding lighter actinides uranium
(238U) or plutonium (239Pu) with neutrons in a nuclear
Reactor.
3. Californium (Cf) - made by bombarding berkelium-249 with neutrons.
4. Mendelevium (Md) - discovered by bombarding einsteinium with
alpha particles in 1955. Bombarding plutonium and
americium targets with lighter ions of carbon and nitrogen.
5. Nobelium (No) - can only be produced in particle accelerators by
bombarding lighter elements with charged particles and
can also produce by bombarding actinide targets to neutron.
6. Lawrencium (Lr) - 266Lr isotopes are produced only as alpha decay
products of dubnium and 255Lr to 262Lr can all be
produced by bombarding actinide (americium to
einsteinium) targets with light ions (from boron to neon).
7. Dubnium (Db) - synthesized the element by bombarding a

31
Activity 5: THINK ABOUT IT
1. What is the contribution of atomic number in synthesizing new elements?
The concept of atomic number is that every element is categorized by the
number of protons in its nucleus. Each element corresponds to a specific
number and vice versa that helped explain the gaps of the periodic table that
were already filled.
2. How are elements synthesized in the laboratory?
They were synthesized in nuclear reactors or particle accelerators. Nuclear
reactions may increase or decrease the number of protons of an atom, thus,
producing new elements.
3. How many elements are manmade? naturally occurring?

32
Out of 118 elements that have been identified in the periodic table, 24 elements
are considered as artificial or manmade and 94 are naturally occurring elements
in the universe.
4. What are the common characteristics of all synthetic elements?
The mechanism for the formation of a synthetic element is to force additional
protons onto the nucleus of an element with an atomic number lower than
95. All synthetic or artificial elements are not stable, but they decay at a long
period of time.
5. What are the uses of synthetic element?
They used to fuel chemical reactors, it can also be used for detectors and
spectrophotometers and some are used in pharmaceutical industries.
Prepared by:
SHAROLYN T. GALURA
Licerio Antiporda Sr National High School-Dalaya Annex
PHYSICAL SCIENCE
Name: ____________________________ Grade Level: _________
Date: _____________________________ Score: ______________
THE POLARITY OF A MOLECULE BASED ON ITS STRUCTURE
A molecule could be a group of atoms. It’s the tiniest unit that may participate
during a chemical reaction.
There are many different types of molecules, and each one of those molecules
may be categorized into polar and non-polar groups. They are separated from each
within the presence or absence of electric poles. Let’s explore further: There are many

33
different molecules, and there are many ways to sort them. A way to classify them
relies on polarity. Polarity means having dipoles, a positive and a negative end. Based
on polarity, molecules can be polar or nonpolar. Some samples of polar molecules are
water, alcohol and ammonia and non-polar molecules are hydrocarbons like gasoline,
methane, ethylene and diatomic molecules (O2, N2, etc.)
Polar molecules have dipoles. Dipole moment is use to measure the polarity
of a chemical bond between two atoms in a molecule. Their dipole moments of polar
molecules don’t add up to zero (or don’t cancel out). In polar molecules, we see that
the charge is not uniformly distributed. It’s electrically asymmetric, that is, the electrical
charges are not equally distributed. When a highly electronegative atom bond with a
comparatively less electronegative atom, a polar molecule is made. It interacts with
other molecules of the same polarity to form solutions. Water and carbon monoxide
are examples of polar molecules.
Nonpolar molecules do not have positive or negative ends. Their dipole
moments add up to zero (they cancel out). It is electrically symmetric, that is the
electrical charges are uniformly distributed. Most of the hydrocarbons liquids are
nonpolar. Nonpolar molecules do not interact the same way. If two combining atoms
have similar or equal electronegativity values, the bond formed is nonpolar. Carbon
tetrachloride and methane are examples of nonpolar molecules.
Source: https://saylordotorg.github.io/text_general-chemistry-principles-patterns-and-applications-v1.0/s12-09-polar-covalent-
bonds.html
Both types of molecules go by “like dissolves like” principle, which means that
polar molecules can dissolve into other polar molecules and nonpolar into other non-
polar molecules. Polar cannot dissolve into non-polar molecules and vice versa.

34
In terms of electronegativity difference, polar molecules has electronegativity
difference between 0.5 & 1.9 while nonpolar molecules have electronegativity
difference of 0.4 & less.
Source: https://www.wikihow.com/Calculate-Electronegativity
Example:
1. HCl
EN of H = 2.1
EN of Cl = 3.0 ΔEN = 0.9
2. H2O
EN of H = 2.1
EN of O = 3.5 ΔEN = 1.4
Elements with the higher EN value become the partial negative pole while
elements with the lower EN value become the partial positive pole. This makes the
molecule a polar molecule.
Generally, you can tell if a molecule is polar or nonpolar based on its structure
or shape and the polarity of the individual bonds present in the molecule. Bond
polarity is a useful concept for describing the sharing of electrons between atoms
• A nonpolar covalent bond is one in which the electrons are shared equally
between two atoms
• A polar covalent bond is one in which one atom has a greater attraction for
the electrons than the other atom. If this relative attraction is great enough, then
the bond is an ionic bond
Example: H2, N2 --- polar
H-H, N-N
HCl, CO ---non-polar

35
CO2 , there is electrical symmetry therefore it is nonpolar.
C-O is polar but if we consider the whole O=C=O due to symmetry then it is
nonpolar.
Emphasize the possibility of having a polar bond between two atoms but if we
consider the structure of the whole molecule it turns out to be nonpolar.
HCN, it is electrically asymmetric therefore it is polar.
Molecular Geometry
The valence shell electron pair repulsion theory or VSEPR theory helps predict
the spatial arrangement of atoms in a polyatomic molecule. The shapes are designed
to minimize the repulsion within a molecule. Symmetry plays an important role in
determining the polarity of a molecule.

36
Source: https://www.pinterest.ph/ali_sajid29/boards/

37
Source:
https://ontrack-media.net/gateway/chemistry/g_cm3l4rs5.html
Guidelines to determine the Valence shell electron pair repulsion theory
(VSEPR) shape of a molecule:
1. Determine the central atom of a molecule. The central atom is the least
electronegative element.
2. Count how many valence electrons the central atom has.
3. Count how many valence electrons the side atoms have.
4. Create the appropriate Lewis structure of the molecule.
5. Using the Lewis structure as a guide, the appropriate VSEPR shape
for the molecule.
6. Note how many electrons are shared and unshared. This will help determine
the appropriate VSEPR shape. Lone pairs has a big factor in making a
molecule polar.

38
Steps in Determining the Polarity of a Molecule
1. Draw the correct Lewis structure and molecular geometry of the molecule.
2. Identify the polarity of each bond present in the molecule. A bond is polar when the
atoms in the bond have different electronegativity. Recall that electronegativity is the
measure of the tendency of an atom to attract a bonding pair of electrons. (You may
use the periodic table to determine the electronegativity values of the atoms.)
3. Draw the dipole moment vectors for polar bonds. The dipole moment vector points
to the more electronegative atom.
Source: http://www.ochempal.org/index.php/alphabetical/c-d/dipole-moment/
4. Determine the sum of the dipole moment vectors. If the dipole moments cancel out
each other, the molecule is nonpolar; otherwise, it is polar.
Example 1:
Carbon dioxide (CO2) is the gas that you exhale.
1. Correct Lewis structure and geometry:
Source: https://www.makethebrainhappy.com/2018/01/lewis-dot-structure-for-CO2.html
2. Oxygen is more electronegative than carbon. Therefore, the C—O bonds are polar.
Source: dashboard.dublinschools.net electronegativity of CO2
3. Since CO2 has a linear symmetrical structure, the dipole moments of the C—O
bonds cancel out.
Therefore, CO2 a nonpolar molecule.
Example 2:

39
Sulfur dioxide (SO2) is a colorless toxic gas formed by burning sulfur in air.
1. Correct Lewis structure and geometry:
Source: https://chemistry.stackexchange.com/questions/87057/lewis-structure-of-SO2
2. Oxygen is more electronegative than sulfur. Therefore, the S—O bonds are polar.
Source: https://www.toppr.com/ask/question/statement-1-the-molecule-SO2-has-a-net-dipolestatement-2-oxygen-has-the-
higher-electronegativity/
3. Since the molecule is bent-shaped, the dipole moments do not cancel out.
Therefore, SO2 is a polar molecule.
Tip: Note that the shape or structure does not directly determine whether the molecule
is polar or nonpolar. However, you need to know the shape of the molecule to know if
the dipole moments cancel out.
Are all bent molecules polar?
Mostly, yes. As aforesaid, bent molecules are asymmetrical just like trigonal
pyramids and that means that they are polar molecules.
The Exceptions
There are a few exceptions to the rules of polar and nonpolar molecules, and
C-H bond is a classic example. This molecule is nonpolar even though the bonds are
slightly polar. Nitrogen trichloride (NCl3) is a rare example. Nitrogen and chlorine are
both electronegative. That’s why their bond (N-Cl) is non-polar. However, when you

40
see the NCl3 molecule, you will see that the nitrogen atom has a single pair of
electrons. This makes the molecule polar by nature. Sulfur trioxide (SO3) and Boron
trihydride (BH3) are other examples. They have polar bonds, but they are nonpolar in
nature. Ozone or trioxygen (O3), on the other hand, has a nonpolar bond but is polar
by nature.
This Learning Activity Sheets composed of different interesting activities which
will make you enjoy learning. Are you ready? You may now start to learn this topic.
Determine if a molecule is polar or non-polar given its structure (S11/12PS-IIIc-15)
Activity 1: Polar and Non-polar Bond
Direction: Identify the following molecules whether polar or nonpolar (it is possible
to have a polar bond between atoms but nonpolar molecule.)
Formula Polar or Nonpolar
Molecules
1. NF
2. HCl
3. N2
4. CS2
5. N2O
6. O3
7. NI3
8. Br2
9. CH2O
10.BCl3

41
Q1. How are polar molecules different from nonpolar?
______________________________________________________________
______________________________________________________________
Q2. What types of elements combine to form a polar molecule and a non-polar
molecule?
______________________________________________________________
______________________________________________________________
Activity 2: Electronegativity Difference
Source: http://curriculum.nismed.upd.edu.ph
Procedure: Complete the table below by determining the electronegativity
difference between the bonded atoms and classify them whether
the molecules are polar or nonpolar.
Complete the table below.
No. Bonded Atoms Electronegativity
Difference
Polar or Nonpolar
Molecules
1. H - O (in H2O)
2. Cl - Cl (in Cl2)
3. N - H (in NH3)

42
4. C - H (in CH4)
5. H – H (in H2)
6. C – P
7. F – Cl
8. Fe – O
9. P - Cl
10. I – I
Q1. What is the difference between polar and nonpolar molecules in terms of their
electronegativity difference?
_____________________________________________________________
_____________________________________________________________
Q2. What is electronegativity?
_____________________________________________________________
_____________________________________________________________
Activity 3: Electronegativity Difference
Procedures:
1. Draw the Lewis structure and describe the molecular geometry of the following
molecules.
2. Determine if a molecule is polar or non-polar given its structure.
Formula Lewis Structure Molecular
Geometry
Polar or
Nonpolar
1. NH3
2. CH4

43
3. PCl5
4. CCl4
5. F2
6. HF
7. O3
8. NCl3
9. CHN
10. CH2O
Q1. Why is it that homo-nuclear diatomic molecules always form nonpolar bond?
______________________________________________________________
______________________________________________________________
Q2. How many nonbonding pairs of electrons did the polar molecules have?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
Q3. How many nonbonding pairs of electrons did the nonpolar molecules have?
______________________________________________________________
______________________________________________________________
______________________________________________________________
Activity 4: True or False

44
Direction: Label the following statements as True or False. If the statement is
false, underline the word/s that make it false and change it to make
it true.
_____ 1. In a nonpolar bond, the electronegativity difference of the bonded
atoms should be 0.4 or less
_____ 2. In a polar bond, electrons are shared between atoms.
_____ 3. A nonpolar molecule has a dipole
_____ 4. In a polar bond, the electronegativity difference of the atoms must be
greater that 1.9
_____ 5. Nonpolar molecules have positive or negative ends.
Activity 5: Who Am I?
Direction: For each of the following Lewis structure, determine the shape/molecular
geometry of each molecule and identify whether it is a polar or nonpolar molecule.
1. 6.
2. 7.
3. 8.

45
4. 9.
5. 10.
Reflection:
1. I learned that ______________________________________________________
___________________________________________________________________
_________________________________________________________
2. I enjoyed most on __________________________________________________
___________________________________________________________________
_________________________________________________________
3. I want to learn more on ____________________________________________
___________________________________________________________________
_________________________________________________________
References:
The Polarity of a Molecule Based on Its Structure by Warlito Zamora Canoy
https://web.facebook.com/notes/physical-science/lesson-31-the-polarity-of-a-molecule-
based-on-its-structure/2001514873198061/?_rdc=1&_rdr
https://www.slideshare.net/MarjorieBrondo/lesson-8-physical science?from_action=save
OldSite Vanden Bout. (2011). VSEPR Theory: Introduction. https://www.youtube.com/
watch?v=keHS-CASZfc

46
www.sachs.gsacrd.ab.ca˃eteacher_download
www.ohsd.net˃cms˃lib˃Centricity˃Domain
www.everettcc.edu˃program˃support˃tutoring-center˃chemistry
https://www.mikeblaber.org/oldwine/chm1045/notes/Bonding/Polarity/Bond05.htm
https://www.pinterest.ph/ali_sajid29/boards/
ANSWER KEY
Activity 1: POLAR AND NONPOLAR BOND
Formula Polar or Nonpolar
Molecules
1. NF Polar
2. HCl Polar
3. N2 Nonpolar
4. CS2 Nonpolar
5. N2O Polar
6. O3 Nonpolar
7. NI3 Polar

47
8. Br2 Nonpolar
9. CH2O Polar
10.BCl3 Polar
Q1. How are polar molecules different from nonpolar molecules?
Polar molecules – are asymmetric, containing lone pairs of electrons on a
central atom; electrons are shared unequally.
Nonpolar – symmetric, all the sides around the central atom are identical-
bonded to the same element with no unshared pair of electrons.
Q2. What types of elements combine to form a polar molecule and a non-polar
molecule?
Polar molecules – between nonmetals with different electronegativities
Nonpolar – between multiple atoms of the same element
Activity 2: ELECTRONEGATIVITY DIFFERENCE
Complete the table.
No. Bonded Atoms Electronegativity
Difference
Polar or Nonpolar
Molecules
1. H - O (in H2O) 1.4 Polar
2. Cl - Cl (in Cl2) 0 Nonpolar
3. N - H (in NH3) 0.9 Polar
4. C - H (in CH4) 0.4 Nonpolar
5. H – H (in H2) 0 Nonpolar
6. C – P 0.4 Nonpolar
7. F – Cl 0.8 Polar
8. Fe – O 1.6 Polar
9. P - Cl 1.0 Polar
10. I – I 0 Nonpolar

48
Q1. What is the difference between polar and nonpolar molecules in terms of their
electronegativity difference?
Polar molecules has electronegativity difference between 0.5 & 1.9 while
nonpolar molecules have electronegativity difference of 0.4 & less.
Q2. What is electronegativity?
Electronegativity is the ability for an atom in a molecule to attract electrons to
itself.
Activity 3: ELECTRONEGATIVITY DIFFERENCE
Formula Lewis Structure Molecular
Geometry
Polar or Nonpolar
1. NH3 Trigonal
pyramidal
Polar
2. CH4 Tetrahedral Nonpolar
3. PCl5 Trigonal
bipyramidal
Polar
4. CCl4 Tetrahedral Nonpolar
5. F2 Linear Nonpolar

49
6. HF Linear Polar
7. O3 Bent Nonpolar
8. NCl3 Trigonal
pyramidal
Polar
9. CHN Linear Polar
10. CH2O
Trigonal planar Polar
Q1. Why is it that homo-nuclear diatomic molecules always form nonpolar bond?
Homo-nuclear diatomic molecules always form nonpolar bond because of the
equal distribution of electrons.
Q2. How many nonbonding pairs of electrons did the polar molecules have?
1 or 2
Q3. How many nonbonding pairs of electrons did the nonpolar molecules have?
Zero (0)
Activity 4: TRUE OR FALSE
True 1. In a nonpolar bond, the electronegativity difference of the bonded
atoms should be 0.4 or less
True 2. In a polar bond, electrons are shared between atoms.
Polar 3. A nonpolar molecule has a dipole.
Between 0.5 to 1.9 4. In a polar bond, the electronegativity difference of the
atoms must be greater than 1.9.
Do not have 5. Nonpolar molecules have positive or negative ends.

50
Activity 5: WHO AM I?
1. 6.
Linear, Polar
Tetrahedral, Polar
2. 7.
Linear, Nonpolar
Trigonal planar, Polar
3. 8.
Linear, Polar
Trigonal pyramidal, Polar
4. 9.
Linear, Nonpolar
Bent, Nonpolar
5. 10.
Linear, Nonpolar
Trigonal pyramidal, Polar

51
Prepared by:
SHAROLYN T. GALURA
Licerio Antiporda Sr National High School- Dalaya Annex
PHYSICAL SCIENCE
Name: ____________________________ Grade Level: _________
Date: _____________________________ Score: ______________
POLARITY OF A MOLECULE TO ITS PROPERTIES
Polarity is a physical property of compounds which relates other physical
properties such as melting and boiling points, solubility, and intermolecular interactions
between molecules. For the most part, there is a direct relationship between the
polarity of a molecule and types of polar or non-polar covalent bonds which are

52
present. In a few cases, a molecule may have polar bonds, but in a symmetrical
arrangement which then gives rise to a non-polar molecule like carbon dioxide.
Properties due to Polarity
In science particularly in chemistry, polarity is a separation of electric
charge leading to a molecule or its chemical groups having an electric dipole moment,
with a negative and positive charged end.
Molecular polarity controls or determines the strength and types
of intermolecular forces of attraction between molecules.
The easiest properties to understand regarding polarity is melting and boiling
points. The more polar a molecule is, the greater its attraction to other molecules like
it. This means that they will stick or attract together tightly even if given a lot of
energy. Ionic molecules are generally solid at room temperature. As a matter of fact,
it can take a lot of energy to melt many of them (>1000°F). Example is NaCl.
Source: http://physicalsciencetext.weebly.com/97---properties-due-to-polarity.html
Polar molecules like water are liquid at room temperature. They have a strong
attraction to each other, but not as strong as ions. Molecules that are nonpolar do not
have the attraction. The only thing that keeps them together is their size. Larger non-
polar molecules like gasoline can be a liquid at room temperatures but become a gas
very easily. Most small. nonpolar molecules (CH4) are gases for a very long period of
time. N2 becomes a liquid at -196°C (-320°F).
The magnitude of these forces is directly proportional to boiling and melting
points. In addition, molecular polarity affects solubility in polar molecules. They are
best solvated by polar solvent molecules and nonpolar molecules are best solvated by

53
nonpolar solvent molecules. The general rule of solubility is Like Dissolves Like. This
explains that polar solvent dissolve polar solute, while nonpolar dissolve
nonpolar. Water (polar) and oil (nonpolar) don’t mix and if the sum of the bond
polarities is zero, the molecule is nonpolar which means the substance is not soluble
in polar solvents like water and will be more soluble in nonpolar solvents like hexane
and it will have relatively low boiling and melting points. However, the sum of the
bond polarities is not zero, the molecule is polar. The greater the sum, the more polar
the molecule and the greater its solubility in polar solvents like water and the higher
its expected boiling and melting points.
Another way to determine if a molecule is polar or nonpolar, it is frequently
useful to look at Lewis structures. Nonpolar compounds will be symmetric, meaning all
the sides around the central atom are identical - bonded to the same element with no
unshared pairs of electrons. Notice that a tetrahedral molecule such as CCl4 is
nonpolar. Another nonpolar molecule shown below is boron trifluoride, BF3. It is a
trigonal planar molecule and all three peripheral atoms are the same.
Source: https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Map%3A_Chemistry_for_Changing_Times_
(Hill_and_McCreary)/04%3A_Chemical_Bonds/4.12%3A_Shapes_and_Properties-_Polar_and_Nonpolar_Molecules
Polar molecules are asymmetric, either containing lone pairs of electrons on a
central atom or having atoms with different electro negativities bonded. This works
well - if you can visualize or picture out the molecular geometry. To know how the
bonds are oriented in space, you must have a strong grasp of Lewis structures and
Nonpolar

54
Valence Shell Electron-Pair Repulsion Theory (VSEPR theory). Assuming you do, you
can look at the structure of each one and decide if it is polar or not - whether you know
the individual atom electronegativity. This is because you know that all bonds between
unlike elements are polar, and in these examples, it doesn't matter which direction the
dipole moment vectors are pointing in or out.
Source: https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Map%3A_Chemistry_for_Changing_Times_
(Hill_and_McCreary)/04%3A_Chemical_Bonds/4.12%3A_Shapes_and_Properties-_Polar_and_Nonpolar_Molecules
Source: http://physicalsciencetext.weebly.com/96---polar-and-non-polar-molecules.html
Polar molecules interact through dipole–dipole intermolecular
forces and hydrogen bonds. Polarity causes a number of physical properties
including surface tension, solubility, and melting and boiling points.
Nonpolar molecules are molecules that lack a charge or contain a partial
charge. They are often made up of many carbon and hydrogen atoms. Due to their
lack of charge, they do not like to interact with polar molecules and when put in solution
Polar

55
with charged or polar molecules, it will separate from them. An example is when you
mix oil and water. Oil is nonpolar and water is polar. This difference in polarity causes
oil to float on top of water rather than mix with it.
Classification
Bonds can fall between one of two extremes – being completely nonpolar or
completely polar. A completely nonpolar bond occurs when the electro negativities are
the same and therefore have a difference of zero. A completely polar bond is more
correctly called an ionic bond, and occurs when the difference between electro
negativities is large enough that one atom actually takes an electron from the other
atom. The terms "polar" and "nonpolar" are usually applied to covalent bonds, that is,
bonds where the polarity is not complete. To determine the polarity of a covalent bond
using numerical value, the difference between the electronegativity of the atoms is
used.
Bond polarity is typically divided into three groups that are loosely based on the
difference in electronegativity between the two bonded atoms.
According to the Pauling scale:
Nonpolar bonds occur when the difference in electronegativity between the two
atoms is less than 0.5
Polar bonds occur when the difference in electronegativity between the two atoms is
roughly between 0.5 and 2.0
Ionic bonds occur when the difference in electronegativity between the two atoms is
greater than 2.0
Valence Shell Electron-Pair Repulsion Theory
Valence shell electron-pair repulsion theory (VSEPR theory) allows us to predict the
molecular structure, including approximate bond angles around a central atom of a
molecule from an examination of the number of bonds and lone electron pairs in its
Lewis structure. The VSEPR model assumes that electron pairs in the valence shell
of a central atom will adopt an arrangement that lessen repulsions between these
electron pairs by maximizing the distance between them. The electrons in the valence
shell of a central atom form either bonding pairs of electrons, located mainly between

56
bonded atoms, or lone pairs. The electrostatic repulsion of these electrons is reduced
or lessen when the various regions of high electron density assume positions as far
from each other as possible.
VSEPR theory predicts the arrangement of electron pairs around each central
atom and, usually, the correct or exact arrangement of atoms in a molecule. We should
understand, however, that the theory only determines electron-pair repulsions. Other
interactions, such as nuclear-nuclear repulsions and nuclear-electron attractions, are
also involved in the final arrangement that atoms adopt in a molecular structure.
Source: https://www.mchmultimedia.com/PhysicalChemistry-help/clientstories/study-tips/a-look-into-bonding-part-1-atoms.html

57
Source: https://www.youtube.com/watch?v=40mG2rQlLpk
Relate the polarity of a molecule to its properties (S11/12PS-IIIc-16)
Activity 1: Compare Me Not
Direction: Determine the difference between polar and nonpolar molecules in terms
of their properties.
Material: Paper and pen

58
Q1. How does polarity affect physical properties?
______________________________________________________________
______________________________________________________________
Q2. How is the polarity of a molecule related to its properties?
______________________________________________________________
______________________________________________________________
Q3. Explain why nonpolar molecules usually have much lower surface tension than
polar ones.
___________________________________________________________________
_________________________________________________________
Activity 2: Think About It!
Direction: Label each of the following as polar or nonpolar molecule and explain
why.
Sample Molecules Polarity Explanation
Properties
1. Boiling point
2. Melting point
3. Solubility
4. Intermolecular
forces of
attraction
5. Surface
tension
Polar
Molecule
Nonpolar
Molecule

59
1. Propane, C3H8
2. Water, H2O
3. Methanol, CH3OH
4. Oxygen, O2
5. Hydrogen cyanide, HCN
Q1. How can you determine if the polarity (polar and nonpolar molecule) is symmetric
or asymmetric?
______________________________________________________________
______________________________________________________________
Activity 3: Describe My Shape
Direction: Given the molecular shape and geometric type of the molecules, describe
each geometric type and identify the polarity of the molecules
Molecules Geometric
Type
Description Polar or
Nonpolar?
1. 1. Linear
2. 2. Bent
3. Tetrahedral

60
4. Trigonal
pyramidal
5. Trigonal planar
Activity 4: Symmetric or Asymmetric?
Direction: Given the Lewis structure of the following molecule, identify whether the
given molecule is symmetric or asymmetric and label if it is polar or nonpolar
molecule.
LEWIS
STRUCTURE
SYMMETRIC or
ASYMMETRIC
POLARITY
(Polar/Nonpolar)
1. N2
2. C2H4
3. HBr
4. OCl2

61
5. SiCl4
Q1. Are all asymmetrical molecules polar?
___________________________________________________________________
_________________________________________________________
Q2. Is BH3 polar or nonpolar? Explain
___________________________________________________________________
_________________________________________________________
Activity 5: True or False
Direction: Label the following statements as True or False. If the statement is
false, underline the word/s that make it false and change it to make it true.
1. Boiling point, melting point, solubility and electro negativities are some of the
properties of the molecules that may affect the polarity of the molecules.
2. The term “Like Dissolves Like” explains that polar solvent dissolve polar solute,
while nonpolar dissolve nonpolar.
3. Polar molecules are symmetric, because having atoms with different electro
negativities bonded.
4. A water molecule, H2O, is a nonpolar molecule because of unequally shared
electrons with the oxygen atom spending more time with electrons than the hydrogen
atoms.
5. Molecular polarity controls or determines the strength and types of intermolecular
forces of attraction between molecules.
Reflection:
1. I learned that _________________________________________________

62
___________________________________________________________________
_________________________________________________________
2. I enjoyed most on ______________________________________________
___________________________________________________________________
_________________________________________________________
___________________________________________________________________
_________________________________________________________
References:
https://www.toppr.com/guides/chemistry/chemical-bonding-and-molecular-
structure/polarity-of-bonds/
http://chemphys.armstrong.edu/P1/polar/polarity.html
physicalsciencetext.weebly.com/97---properties-due-to-polarity.html
https://en.wikipedia.org/wiki/Chemical_polarity
http://physicalsciencetext.weebly.com/96---polar-and-non-polar-molecules.html
https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textb
ook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Physical
_Properties_of_Matter/Atomic_and_Molecular_Properties/Molecular_Polarity

63
https://en.wikipedia.org/wiki/Chemical_polarity#Polar_molecules
https://www.youtube.com/watch?v=40mG2rQlLpk
https://opentextbc.ca/chemistry/chapter/7-6-molecular-structure-and-polarity/
https://www.mchmultimedia.com/PhysicalChemistry-help/clientstories/study-tips/a-
look-into-bonding-part-1-atoms.html
ANSWER KEY
Activity 1: COMPARE ME NOT

64
Q1. How does polarity affect physical properties?
The polarity of a molecule has a strong effect on its physical properties. Molecules
which are more polar have stronger intermolecular forces between them and have
higher boiling points as well as other different physical properties.
Q2. How is the polarity of a molecule related to its properties?
Polarity refers to the physical properties of compounds such as boiling point, melting
points, surface tension and their solubility. The polarity of bonds is caused due to the
interaction of the bonds between molecules and atoms with different electro
negativities.
Q3. Explain why nonpolar molecules usually have much lower surface tension than
polar ones.
Because the molecules aren't attracted to each other as much as in polar molecules,
these molecules are much less likely to have high surface tension.
Activity 2: THINK ABOUT IT!
Sample Molecules Polarity Explanation
1. Propane, C3H8 Nonpolar It is symmetric, with H
atoms bonded to every
side around the central
Properties
1. Boiling point
2. Melting point
3. Solubility
4. Intermolecular
forces of
attraction
5. Surface
tension
Polar
Molecule
1. High boiling
point
2. High melting
point
3. Soluble in
Polar solvent
4. Strong
intermolecular
forces of
attraction
5. High Surface
Tension
Nonpolar
Molecule
1. Low boiling
point
2. Low melting
point
3. Soluble in
non-
Polar solvent
4. Weak
intermolecular
forces of
attraction
5. Low Surface
Tension

65
atoms and has no
unshared pairs of
electrons
2. Water, H2O Polar Any molecule with lone
pairs of electrons
around the central atom
is polar.
3. Methanol, CH3OH Polar This is not symmetric.
The Nitrogen and
Hydrogen have
different
electronegativity values
creating uneven pull of
the electrons
4. Oxygen, O2 Nonpolar The molecule is
symmetric. The two
oxygen atoms pull on
the electrons by the
same value
5. Hydrogen cyanide,
HCN
Polar It is not symmetric.
(there is no hydroxyl
group -OH and there is
only one H not 3)
Q1. How can you determine if the polarity (polar and nonpolar molecule) is symmetric
or asymmetric?
Nonpolar molecules are symmetric because there is no unshared electrons while polar
molecules are asymmetric because it contain lone pairs of electrons on the central
atom or having atoms with different electronegativities bonded.
Activity 3: DESCRIBE MY SHAPE
Molecules Geometric
Type
Description Polar or
Nonpolar?
1. 1. Linear Two atoms
symmetrically
distributed around the
central atom. Results
in a bond angle of
exactly 1800
.
polar
2. 2. Bent Two atoms
symmetrical
Polar

66
central atom with a
lone pair of the central
atom. Results in a
bond angle slightly
less than 1200
3. Tetrahedral Four outer atoms
symmetrically
central atom. Forms a
regular tetrahedron.
Results in a bond
angle exactly 109.50
Nonpolar
4. Trigonal
pyramidal
Three outer atoms
symmetrically
central atom with one
lone pair on the
central atom. Results
in a bond angle
slightly less than
109.50
Polar
5. Trigonal
planar
Three atoms
symmetrically
central atom without
any lone pairs on the
central. All of the
atoms lies in the
same plane. Results
in a bond angle of
exactly 1200
Nonpolar
Activity 4: SYMMETRIC OR ASYMMETRIC?
LEWIS
STRUCTURE
SYMMETRIC or
ASYMMETRIC
POLARITY
(Polar/Nonpolar)

67
1. N2 Symmetric Nonpolar
2. C2H4 Symmetric Nonpolar
3. HBr Asymmetric Polar
4. OCl2 Asymmetric Polar
5. SiCl4 Symmetric Nonpolar
Q1. Are all asymmetrical molecules polar?
Yes, because it consists of lone pairs of electrons on a central atom or having atoms
with different electro negativities bonded.
Q2. Is BH3 polar or nonpolar? Explain
Nonpolar because it is completely symmetrical.
Activity 5: TRUE OR FALSE
1. Boiling point, melting point, solubility, surface tension and electro negativities are
some of the properties of the molecules that may affect the polarity of the molecules.
• Intermolecular forces of attraction
2. The term “Like Dissolves Like” explains that polar solvent dissolve polar solute,
while nonpolar dissolve nonpolar.

68
• True
3. Polar molecules are symmetric, because having atoms with different electro
negativities bonded.
• Asymmetric
4. A water molecule, H2O, is a nonpolar molecule because of unequally shared
electrons with the oxygen atom spending more time with electrons than the hydrogen
atoms.
• Polar molecule
5. Molecular polarity controls or determines the strength and types of intermolecular
forces of attraction between molecules.
• True
Prepared by:
SHAROLYN T. GALURA
Licerio Antiporda Sr National High School- Dalaya Annex
PHYSICAL SCIENCE
Name: ____________________________ Grade Level: _________
Date: _____________________________ Score: ______________

69
THE GENERAL TYPES OF INTERMOLECULAR FORCES
What holds multiple water molecules to each other? Why does a substance
have its distinctive phase? These are conceivably some of the questions we ignore
and fail to appreciate. Considering that fact, these learning activity sheets were
designed to grow your interest in science concepts we often disregard and learn more
about them.
By now you should be comfortable with the idea of a chemical bond. Both ionic
and covalent bonds form because atoms want to have the stable configuration of noble
gases. Example: Covalent bonds hold the hydrogen and oxygen atoms together in a
single water molecule. Break bonds and you change the chemical nature of that
substance.
In these learning activity sheets you will find out the different types of
intermolecular forces (IMF’s) that plays an unobtrusive role in all matters we use in our
daily life.
The Four General Types of intermolecular forces
1. London Dispersion Forces/ Van der Waals Dispersion Forces
2. Dipole-Dipole Interactions
3. Ion- ion Interactions
4. Hydrogen Bonding Interactions
1. London Dispersion Forces(LDF)
This type of intermolecular force is very weak and acts in short distances. It is
formed due to the attraction between the positively charged nucleus of an atom with
the negatively charged electron cloud of a nearby atom. This interaction creates an
induced dipole.

70
In addition, dispersion forces cause nonpolar substances to condense to liquids
and to freeze into solids when the temperature is lowered sufficiently. Because of the
constant motion of the electrons, an atom or molecule can develop a temporary
(instantaneous) dipole when its electrons are distributed unsymmetrically about the
nucleus.
https://www.chem.purdue.edu/gchelp/liquids/disperse.html
We could discount intermolecular interactions between gas-phase molecules
because these molecules are mostly far apart and moving rapidly relative to each
other. In the liquid phases, all molecules interact with one another. The stronger the
interaction between a molecule and a pure liquid, the greater will be the solubility of
the molecule in the liquid.
All molecules interact with each other through London dispersion forces, or
induced dipole interactions. In figure A.1, a 2-atom molecule collides with a 3-atom
molecule. The electron cloud of the first molecule repels the electron cloud of the
molecule it strikes, causing a displacement of some electron density away from the
nucleus. The nucleus is then poorly shielded by its own electrons and attracts the
electron cloud of the first molecule.
Figure A.1
Image: http://butane.chem.uiuc.edu/pshapley/genchem1/l20/1.html

71
Both molecules now have a small dipole moment that was induced by molecular
collision.
2. Dipole- Dipole Forces(DDF)
Molecules with permanent dipoles can interact with other polar molecules
through dipole-dipole interactions. Again this is electrostatic in nature. The molecular
dipole vector points towards high electron density.
Average dipole-dipole interaction is relatively weak, around 4kJ/ mol. This
interaction is effective over a very short range. The strength of dipole-dipole
interaction is inversely proportional to distance raised to the fourth power (d4
).
Reminder: Polar molecules are also referred to as “dipoles” due to their two poles.
Without dispersion forces substances would not be able to condense to
liquid and solid phase.
Visit: Want to learn more about dispersion forces?
Visit: https://www.youtube.com/watch?v=1iYKajMsYPY
Dipole-dipole interactions occur between polar molecules. This is due
to the partial positive pole and the partial negative pole of the molecule.

72
3. Ion- Dipole Forces(IDF)
When an ionic compound such as NaCl dissolves in water, the water molecules
arrange their oppositely charged dipole to be attracted to the fully charged ion, creating
a very strong attractive force called an ion-dipole force. The partial negative charge on
the water molecule is attracted to the fully charged positive sodium ion (Na+). The
partial positive charge on the water molecule is attracted to the fully charged negative
chloride ion (Cl-).
Electrostatic attractive forces that create the ionic bond in NaCl are ~10 times
stronger than a single ion-dipole force that is created between the ion and water. Only
if enough water molecules surround the ion creating many, many ion-dipole attractions
can the water molecule pull the ion away from the ionic crystal lattice, dissolving the
ionic compound.
4. Hydrogen Bonding Forces (HDF)
Visit: Want to learn more about dipole-dipole interactions?
Visit: https://www.youtube.com/watch?v=zOvnu0KYyxo
An ion-dipole interaction is the result of an electrostatic interaction
between a charged ion and a molecule that has a dipole. It is an
attractive force that is commonly found in solutions, especially ionic
compounds dissolved in polar liquids.
Visit: Want to learn more about ion -dipole interactions?
Visit: https://www.youtube.com/watch?v=1zhyHv2NJ04

73
Hydrogen that is bonded to very electronegative elements (F, O, or N) is highly
electron deficient. It acts as a Lewis acid and interacts with basic sites in other
molecules. The hydrogen bonding interaction is stronger than dipole-dipole
interactions. Again, it adds to the existing London dispersion forces to stabilize
molecules in solution.
The covalent bond that link H and oxygen together is known as coordinate
covalent bond, Oxygen bonds with H using its lone pair of electron.
Hydrogen bonding interactions are stronger than the other interactions that take
place in solution, with an energy of 5 to 30 kJ/mol for each interaction. It has some
aspects of dipole-dipole interactions and some aspects of covalent bonding. For
example, the interaction between X and H in X---H-Y is less than the sum of the radii
of the two atoms but more than their covalent bond distance.
Hydrogen bond is a very strong dipole-dipole interaction. Hydrogen bond
occurs in polar molecules containing H and any one of the highly
electronegative elements, in particular F, O, N.
Visit: Want to learn more about hydrogen bonds?
Vist : https://www.youtube.com/watch?v=RSRiywp9v9w
https://www.youtube.com/watch?v=b74-zoUz-a8
https://www.youtube.com/watch?v=b74-zoUz-a8

74
Describe general types of intermolecular forces (S11/12PS-IIIc-d-17)
Activity 1: Sticking Newspaper
This activity will give you an opportunity to investigate how intermolecular
forces affect a piece of newspaper, analyze intermolecular forces and chemical
bonding and demonstrate your knowledge of the forces at work between different
molecules.
Objective:
Investigate how intermolecular forces affect a piece of newspaper.
You need:
1. Newspaper strips
2. All purpose adhesive or contact cement(rugby)
3. Baby powder
4. A pair of scissors
Instructions:
1. Coat one side of the newspaper with all purpose adhesive and then lightly
apply baby powder to the same side.
2. Fold the newspaper in half so that the all purpose adhesive side is
touching. Notice that the paper does not stick together.

75
3. Then, holding the newspaper in the air, cut a small piece of the newspaper
off the bottom. Hold on to one piece of the paper and let the other piece
drop. Notice that the paper now sticks together.
4. Continue cutting the paper and examining what is happening before moving
on to the discussion questions.
Discussion Questions:
1. What forces are at work when the paper doesn't stick together?
______________________________________________________________
______________________________________________________________
______________________________________________________________
2. Why does cutting the paper change the forces between the molecules?
______________________________________________________________
______________________________________________________________
______________________________________________________________

76
Activity 2: Intermolecular Forces
Objective:
Determine the polarity and the strongest intermolecular force in the
molecules.
Instruction:
Indicate the strongest type of intermolecular force (LDF, DDF, HBF, or IDF)
between the molecules in the following:
Polar or Non-Polar?
Strongest
Intermolecular Force
A. CO2
B. PF3
C. HF
D. CH4
E. KBr in H2O
Reflection:
1. I learned that ______________________________________________________
___________________________________________________________________
___________________________________________________________________
2. I enjoyed most on___________________________________________________
___________________________________________________________________
___________________________________________________________________.
3. I want to learn more on ______________________________________________

77
___________________________________________________________________
___________________________________________________________________.
References
Types of Intermolecular Forces, Professor Patricia Shapley (2011)
http://butane.chem.uiuc.edu/pshapley/genchem1/l20/1.html
London Dispersion Forces, Bozeman Science ( 2013)
https://www.youtube.com/watch?v=1iYKajMsYPY
https://chem.libretexts.org/Bookshelves/General_Chemistry/Map%3A_Chemis
try_The_Central_Science_(Brown_et_al.)/11%3A_Liquids_and_Intermolecula
r_Forces/11.S%3A_Liquids_and_Intermolecular_Forces_(Summary)
Intermolecular Forces Magic Trick, FlinnScientific (2012)
http://elearning.flinnsci.com

78
Answer Key
Independent Activity 1
Discussion Question Answers:
1. None. The powder will absorb any remaining moisture and create a thin,
slippery barrier that will keep the newspaper from sticking to itself.
2. When you cut the newspaper you put intense pressure on it allowing the
rubber cement molecules at the tip of the newspaper to stick together.
Independent Activity 2
Answers: A) nonpolar, LDF; B) polar, DDF; C) polar, HBF; D) nonpolar, LDF; E)
polar,IDF

79
Prepared by:
ALDRIN GRAGEDA
Pattao National High School
PHYSICAL SCIENCE
Name: ____________________________ Grade Level: _________
Date: _____________________________ Score: ______________
Effects of Intermolecular Forces on the Properties of Substances
Imagine you just broke your favorite lamp. You have several different types of
glue to put it back together. If you choose a weaker glue, it won't take much force for

80
the lamp to fall apart again, while using a stronger glue would require a lot more force
to break that bond.
Intermolecular forces are like the glue, only instead of holding a lamp together,
intermolecular forces hold molecules together. There are strong and weak forces; the
stronger the force, the more energy is required to break those molecules apart from
each other.
So, if two molecules are only connected using van der Waals dispersion forces,
then it would require very little energy to break those molecules apart from each other.
On the other hand, if two molecules are connected using ionic bonds, it takes a whole
lot more energy to break those two apart.
In these learning activity sheets, you will learn and understand how
intermolecular forces affect the physical properties of substances.
Intermolecular Forces and Physical Properties
Stronger intermolecular forces will result in a higher physical properties such as
higher melting or boiling points, which require breaking molecules apart. Higher
intermolecular forces also leads to a higher freezing point, but since we are talking
about lowering the temperature for freezing points, we often say that lower
intermolecular forces requires lowering the temperature more.
Since a higher vapor pressure means that it is easier to vaporize a compound,
this means that lower intermolecular forces leads to a higher vapor pressure.
Viscosity
When you pour a glass of water, or fill a car with gasoline, you observe that
water and gasoline flow freely. But when you pour syrup on pancakes or add oil to a
car engine, you note that syrup and motor oil do not flow as readily. The viscosity of
a liquid is a measure of its resistance to flow. Water, gasoline, and other liquids that
flow freely have a low viscosity. Honey, syrup, motor oil, and other liquids that do not
flow freely, like those shown in Figure 1, have higher viscosities. We can measure
viscosity by measuring the rate at which a metal ball falls through a liquid (the ball falls

81
more slowly through a more viscous liquid) or by measuring the rate at which a liquid
flows through a narrow tube (more viscous liquids flow more slowly).
Figure 1. (a) Honey and (b) motor oil are examples of liquids with high viscosities; they
flow slowly. (credit a: modification of work by Scott Bauer; credit b: modification of work
by David Nagy)
The IMFs between the molecules of a liquid, the size and shape of the
molecules, and the temperature determine how easily a liquid flows. As Table 2 shows,
the more structurally complex are the molecules in a liquid and the stronger the IMFs
between them, the more difficult it is for them to move past each other and the greater
is the viscosity of the liquid. As the temperature increases, the molecules move more
rapidly and their kinetic energies are better able to overcome the forces that hold them
together; thus, the viscosity of the liquid decreases.
Substance Formula Viscosity (mPa·s)
Water H2O 0.890
mercury Hg 1.526
ethanol C2H5OH 1.074
Octane C8H18 0.508

82
Substance Formula Viscosity (mPa·s)
ethylene glycol CH2(OH)CH2(OH) 16.1
Honey Variable ~2,000–10,000
motor oil Variable ~50–500
Table 2. Viscosities of Common Substances at 25 °C
Process Questions:
Put a check in the box opposite the correct answer.
1. What happens to the viscosity of a liquid when its temeperature is raised?
 The viscosity of the liquid increases.
 The viscosity of the liquid stays the same.
 The viscosity of the liquid decreases.
 The temperature of a liquid does NOT raise.
2. What is the definition of Low-viscosity?
 When a solid, quickly flows out of its container.
 When a fluid, slowly empties from its container.
 When a fluid quickly flows out of its container.
 Answer is not shown
3. Viscosity is determined mostly by what?
 Density
 The shape of the molecules of the liquid.
 Mass/Volume
 Density*Volume
Surface Tension

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A phenomenon caused by cohesive forces (intermolecular forces) between
molecules allowing liquids to create a thin film on its surface. This causes liquids to
acquire a certain shape when put on a container or dropped on surfaces.
In a container, the bulk of a liquid has a balance of intermolecular forces in all
direction. There is a net inward force on the surface since there are no liquids there.
This creates surface tension. Stronger intermolecular bonds equates to stronger
surface tension.
Among common liquids, water exhibits a distinctly high surface tension due to
strong hydrogen bonding between its molecules. As a result of this high surface
tension, the surface of water represents a relatively “tough skin” that can withstand
considerable force without breaking. A steel needle carefully placed on water will float.
Figure 2. Attractive forces result in a spherical water drop that minimizes surface area;
cohesive forces hold the sphere together; adhesive forces keep the drop attached to
the web.
Some insects, like the one shown in Figure 3, even though they are denser than water,
move on its surface because they are supported by the surface tension.
(credit photo: modification of work by “OliBac”/Flickr)

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