Atoms and Bonding

σ-

O

H H
σ+ σ+

Atoms and Bonding
Intro to Chemistry
MrT
staylor@canacad.ac.jp

It has electrons and
protons in the nucleus
and neutrons outside.

The electrons are the
heaviest part, which is
why they’re outside.

The nucleus is overall
positive and the electrons
are negatively charged.

Clipart people from: http://www.clker.com/search/krug/1

Atoms and Bonding
Unit Questions: “How can we know what we cannot see?”
Enduring Understandings:
• Patterns and structures lead to predictability
Areas of interaction:
Human Ingenuity
The Periodic Table is an amazing feat of the scientific method and reason.

Criterion Assessment Tasks
B: Communication Sports Drinks Lab
C: Knowledge & Understanding Mystery elements bonding task (test conditions)

Quia Review Quizzes:
• 2.1 Atoms, ions, isotopes
• 2.2 Periodic Table and structure
• 2.3 Ionic and Covalent Bonding
• 2.4 Intermolecular forces

Atoms and Bonding
Assessment Statements
• Define valence electrons and outline the duet
• Describe the components of the atom
and octet rules.
(protons, neutrons, electrons), in terms of
• Draw Lewis dot structures for the valence
size and charge.
electrons of elements on the periodic table.
• Outline the structure of the atom.
• Deduce whether two elements will form an
• Distinguish between atomic number, mass
number and atomic mass.
ionic or covalent compounds from their
position on the periodic table
• Deduce the atomic number and mass
• Explain the formation of ionic bonds.
number of an element from its position on
• Describe the properties of ionic compounds.
the periodic table.
• Describe metallic bonds and their properties.
• Outline the formation of isotopes, using
• Define molecule.
examples.
• Explain the formation of covalent bonds,
• Distinguish between atoms and ions.
using Lewis dot structures.
• Explain how cations and anions are formed,
• Describe the properties of covalently bonded
with examples.
molecules.
• Outline the organisation of the periodic
• Outline how covalent bonding leads to polar
table in terms of groups, periods and
bonds and molecules.
families.
• Explain hydrogen bonding in water as an
• Describe the trend in atomic structure
through the periodic table.
example of dipole-dipole attractions.
• Describe Van der Waal's Forces.

Build an Atom
Run the simulation and build the following:
1. a hydrogen atom.
2. the hydrogen cation.
3. helium.
4. a stable isotope of helium.
5. an unstable istotope of helium.

Answer the following:
1. Which subatomic particle determines
the element’s atomic number? Build an Atom, from PhET. Click Run Now.
http://phet.colorado.edu/en/simulation/build-an-atom
2. Which two subatomic particles
determine the element’s mass number? If you’re done:
3. How is ionic charge (net charge) What level can you reach on the game?
determined and what makes an ion?
4. What is an isotope and how is it made?

Then test yourself (and research further):
http://www.quia.com/quiz/3320413.html
(firstnamelastname230, milk)

- Atom
Nucleus and electron cloud
Electron (e-)
(mass = negligible, charge: -1)

Neutron (n0)
+ (mass = 1amu*, charge: 0)
Nucleus
contains nucleons + Proton (p+)
(mass = 1amu, charge: +1)

Mass number is the Atomic number is Atomic mass is the
total number of the number of mean mass of an
protons plus protons. This element’s atom
neutrons. defines the based on isotopes.
element.

-
*atomic mass unit (neutrons are slightly more than 1amu)

-
Atomic number
is the number of protons.

2
He
+ helium
+
4.00
Atomic mass
is the mean mass of an
element’s atom based on
isotopes.

Different periodic tables place the atomic
number, atomic mass and mass number in
- different positions, so pay attention to the key.

What’s this?

?
+ ?
?
?

What’s this? An atom of hydrogen has one
proton and one electron only.

1
+ H
hydrogen
1.01
Why the 1.01?
In nature some isotopes of hydrogen exist.
These have 1 neutron (deuterium, mass 2amu) or 2 neutrons (tritium, mass 3amu)
How would you change the diagram to show each of these isotopes?

What’s the mean number
of legs per person in:
• this class?
• the world?

Image: 'Stacked'
http://www.flickr.com/photos/17731548@N00/2153132167
Found on flickrcc.net

What’s the mean number
of legs per person in:
• this class?
• the world?

Slightly less than one!
Why?

Image: 'Stacked'
http://www.flickr.com/photos/17731548@N00/2153132167
Found on flickrcc.net

What’s this? This ion of hydrogen has one proton
only. An electron has been lost.

1
+ H +
hydrogen
1.01

The overall charge of this ion is +1.
It is a cation.

- What do you
think?
+
+
+

It has 2 e-, but 3n0, so it must
- be an isotope of helium

It has 3 p+, so it must
be an ion of lithium
It has 2 e-, so it must
be helium

-

+ +
+
-

What do these represent?
-
+
+ +
-

-

+ +
+
-
An atom of hydrogen has one proton An atom of helium has two protons,
and one electron only. two neutrons and two electrons.

-
+
+ +
-
An ion of hydrogen has one This isotope of helium has two protons,
proton only – and therefore an one neutron and two electrons.
overall charge of +1

mass number = 12 13 What do you
? ? think?
atomic number = 6 Charge = 0 6 Charge = 0

They are both the same element,
but have different mass numbers,
so one must be an ion.

The atomic mass of the
second element is 13, so it
must be aluminium

Its atomic number is 6, so they
must both be carbon

Marshmallow Isotopes
neutrons
1. Make a hydrogen nucleus (a proton). nucleons
2. Make an alpha particle (helium nucleus) protons
Use a lick to stick.
Sticking forces in nuclei are weak. What are they? You need white and
pink marshmallows
This is called helium-4, as it has four nucleons.
3. Make a particle of the isotope helium-3. +
What is different? +
4. He-5 is an unstable isotope. The alpha-particle
Make it and then suggest why it is unstable.

5. C-12 is the main stable isotope of carbon. Make it.
What other isotopes of carbon are there? What are their uses?

6. In the first few minutes of the universe, alpha particles formed.
New elements can be made from combining alpha particles.
Combine your He-4 with a C-12. What element have you made?

Adapted from: http://www.lbl.gov/abc/marsh-nuclei/index.html Image from http://www.hancocks.co.uk/

Neutrons determine nuclear properties
Have a go at this at home if you need more consolidation on isotopes, neutrons and mass number.

Recreate some of the atoms and isotopes you
made in the marshmallow activity.

How does neutron number affect mass
number of the atom?

Are all isotopes of an element equally
abundant in nature?

What is nuclear ‘stability’?

Isotopes & Atomic Mass, from PhET. Click Run Now.
http://phet.colorado.edu/en/simulation/isotopes-and-atomic-mass

The number of neutrons does not always equal the number of protons in a stable
element. As proton number increases, an increasing number of neutrons is needed
to keep the atom stable. If there are too many or too few neutrons, it is unstable.

Not all periodic atomic number

tables organise the
numbers around the
elements in the same
way. mass number
symbol

You must pay name

attention to the key!

mass number = 127 131 What do you
? ? think?

Check the key! They are both isotopes of iodine.
They have different numbers of
neutrons and protons.

They are both isotopes of
iodine. They have different
numbers of neutrons.

They have the same atomic
numbers but different mass
numbers. They are ions.

Iodine has many isotopes.
mass number = 127 131
I I

Iodine-127 Iodine-131
Protons: 53 Protons: 53
Neutrons: 74 Neutrons: 78

Stable Unstable Radioisotope used in treating
Abundant Artifical thyroid cancer.

The number of neutrons does not always equal the number of protons in a stable
element. As proton number increases, an increasing number of neutrons is needed
to keep the atom stable. If there are too many or too few neutrons, it is unstable.

mass number = 12 Atom, Ion or
C Isotope?
atomic number = 6 Charge = 0

1
?
1 Charge = +1

C Isotope?

1 238
H ?
1 Charge = +1 92 Charge = 0

H+ ion

C Isotope?

1 238 235
H U ?
1 Charge = +1 92 Charge = 0 92 Charge = 0

H+ ion Uranium

C Isotope?

1 238 235 60
H U U ?
1 Charge = +1 92 Charge = 0 92 Charge = 0 27 Charge = 0

H+ ion Uranium Uranium isotope

C Isotope?

1 238 235 60
H U U Co

H+ ion Uranium Uranium isotope Cobalt isotope

16
?
8 Charge = 2-

C Isotope?

1 238 235 60
H U U Co


16 238
O ?
8 Charge = 2- 94 Charge = 0

Oxygen ion

C Isotope?

1 238 235 60
H U U Co


16 238 40
O Pu ?
8 Charge = 2- 94 Charge = 0 20 Charge = 2+

Oxygen ion Plutonium isotope

C Isotope?

1 238 235 60
H U U Co


16 238 40 47
O Pu Ca ?
8 Charge = 2- 94 Charge = 0 20 Charge = 2+ 20 Charge = 0

Oxygen ion Plutonium isotope Calcium ion

C Isotope?

1 238 235 60
H U U Co


16 238 40 47
O Pu Ca Ca
8 Charge = 2- 94 Charge = 0 20 Charge = 2+ 20 Charge = 0

Oxygen ion Plutonium isotope Calcium ion Calcium isotope

What are they?
How do we draw them?

IONS
How do we name them?

How do they make bonds?

Electrons determine chemical properties
An atom of helium has two protons, two
neutrons and two electrons. -
It is a small atom, with an electron ‘shell’ which 2p+
can hold only 2 electrons. 2n0

Because the ‘shell’ is full, He is stable and -
unreactive – it is a noble gas.
The inner shells ‘fill’ first, as the electrons are - -
attracted to the positive nucleus. -

Larger atoms have bigger shells. However, the
outermost shell holds maximum 8 electrons. 9p+ -
- 9n0 -
What is this atom?

How might it become more stable?
-
- -

Ions have unbalanced protons and electrons
-
H atom 1p+
0n0

- -
-
F atom
9p+ -
- 9n0 -

-
- -


H+ ion 1p+
0n0

Positively charged ions are cations.
(Think: cats make old ladies happy)
- -
-
F- ion
- 9p+ -
Negatively charged ions are anions.
- 9n0 -
(Think: A Negative ION)

-
- -

Octet Rule
Atoms in a compound will tend to have the
electron configuration of a noble gas:
Eight electrons in the outer (valence) shell.

Duet Rule
The inner shell can hold a maximum two electrons
– the configuration of helium.

Atoms and the periodic table
Group 1: Alkali metals
columns Group 2: Alkaline earth metals
are groups Group 7: Halogens (sometimes called 17)
Group 8: Noble gases (sometimes 18 or 0)

orphan
hydrogen

rows are
periods

Lanthanides
Actinoids

Interactive periodic table from: http://www.ptable.com/

Common ions:

Positively charged ions are cations. Negatively charged ions are anions.
(Think: cats make old ladies happy) (Think: A Negative ION)

What’s the difference between the ions in purple and those in black?
Compare the elemental ions to the periodic table. Can you describe a trend?
Can you explain why the elements above form these specific ions?

What’s the relationship between atomic structure and the periodic table?

+1 +2 Ionic charges are in red. +3 -3 -2 -1

metals non-metals

transition metals

Periodic Table from the IBDP Chemistry Data Booklet

What’s the relationship between atomic structure and the periodic table?

Interactive periodic table from: http://www.footprints-science.co.uk/flash/periodic2.swf

Atoms and the periodic table
Group 1: Alkali metals
columns Group 2: Alkaline earth metals
are groups Group 17: Halogens
Group 18: Noble gases

orphan
hydrogen

rows are
periods

Lanthanides
Actinoids


Valence Electrons & Configurations
In the first period (H and He), there is one
small electron shell. It can hold up to two
electrons – a duet.

As we move down each period, we
add an electron shell.
The outer shell can hold
up to 8 electrons.

4 shells, 1 valence
electron

Valence electrons are the electrons in
the outer shell only. They are used in
bonding.

Once the outer shell is full, the atom is
stable. This is the octet rule.


Complete the pattern…
H He

Li Be B C N O F Ne
What do the dots represent?

What is the relationship with periodic table?

Can you predict the pattern for aluminium?

Lewis dot configurations
These dots show the number of valence electrons in an atom.
H We can use them to predict bond types as well as the He
structure of a compound.

Li Be B C N O F Ne
What is the relationship with periodic table?
Elements in the same group have the same All the Lewis dots:
number of valence electrons.

Can you predict the pattern for aluminium?

Al

http://www.roymech.co.uk/Related/Chemistry/Lewis_dot_structure.html

What’s in your sports drinks?
Sports drinks contain ions to help with rehydration (if you really need it).
Two of their main ingredients are sugar (sucrose) and salt (sodium chloride).

In this investigation we will:
• Determine whether sugar or salt is ionic
• Compare the ion concentrations of two drinks

https://docs.google.com/presentation/d/1Hqs6AMjlx5KBGWWSzOLBSBbO2mzDqw17CkMSdB
hSAcQ
Pocari Sweat and Aquarius bottles from
http://jin.jcic.or.jp/en/ranking/near_water_small_pet_bottle_pouch/

Bonding is the attraction between atoms.
Atoms are stable when they have a full valence shell.
In ionic bonds, electrons are transferred to achieve this.
In covalent, electrons are shared.
The result are forces of attraction.

Bonds:
• Ionic
• Covalent
• Metallic

Inter-molecular forces:
• Dipole-dipole bonds
• Hydrogen bonds
• Van der Waal’s forces

http://www.kentchemistry.com/links/bonding/bondingflashes/bond_types.swf

Ionic or covalent bonds?
Binary compounds contain two elements.
Metal + non-metal, the bonding will be ionic.
If both are non-metals, bonding is covalent.
non-metals

metals

So what about these compounds?

lithium fluoride _____________ nitrogen dioxide _____________
carbon dioxide _____________ water _____________
magnesium oxide ____________ methane (CH4) _____________
sodium chloride _____________ lead iodide _____________

Periodic table from the BBC. http://goo.gl/1rrCk

Ionic or covalent bonds?
Binary compounds contain two elements.
Metal + non-metal, the bonding will be ionic.
If both are non-metals, bonding is covalent.
non-metals

metals

So what about these compounds?

lithium fluoride ionic nitrogen dioxide covalent
carbon dioxide covalent water covalent
magnesium oxide ionic methane (CH4) covalent
sodium chloride ionic lead iodide ionic

Periodic table from the BBC. http://goo.gl/1rrCk

Ionic Bonding
Forms between a metal and a non-metal.
Metal cations(+) donate electron(s) to non-
metal anions(-).

Li F
+ -
cation Li F anion

The metal has lost its lone electron and the
non-metal has gained. They each now have
filled outer valence shells.
Cations attract anions – the atoms are held
together by this attraction – the ionic bond.
+ -
Li F
http://www.footprints-science.co.uk/ionic.htm

Almost full? Get some more. Almost empty? Get rid.
Draw the electron arrangements on these shells.
State the number of valence electrons and draw a Lewis dot configuration.
Deduce whether they will form an anion or a cation.

Oxygen Chlorine

Aluminium Beryllium


Oxygen Chlorine
8 protons, 8 electrons,
6 valence electrons.

Lewis dot: O
2-
O Almost full- gain two electrons
and form an anion.

Aluminium Magnesium

Al


Oxygen Chlorine
6 valence electrons.

Lewis dot: O
2-
O Almost full- gain two electrons
and form an anion.

Aluminium Magnesium

Al 3 valence electrons.

Lewis dot: Al
3+
Al Almost empty- lose three
electrons and form a cation.

Ionic Bonding
Cations Anions
+1 +2 +3 -3 -2 -1
+ 2+ 3+ 3- 2- -
H Mg Al N O Cl
Li+ Ca2+ Fe3+ P3- S2- Br-
In an ionic bond, the charges must balance. + 2+ 3- 2- -
Na Fe PO4 CO3 I
Ions can be elemental or polyatomic – it is K
+
Cu
2+
SO4
2-
NO3
-

the charge which matters. NH4
+
Zn
2+
HCO3
-

2+ -
Pb OH
What combinations of ions are needed to
make the following compounds?
• Sodium chloride
one of each ion gives a
• Lithium iodide Na+ Cl- balanced charge
• Calcium carbonate
• Sodium hydroxide
• Iron (III) oxide

Ionic bonding works in 3-D, so
ionic compounds form crystal
structures. They are strong and
can form aqueous solutions. They
are good electrical conductors
when dissolved or molten.

Ionic Bonding
Cations Anions
+1 +2 +3 -3 -2 -1
+ 2+ 3+ 3- 2- -
H Mg Al N O Cl
In an ionic bond, the charges must balance. + 2+ 3- 2- -
Na Fe PO4 CO3 I
Ions can be elemental or polyatomic – it is K
+
Cu
2+
SO4
2-
NO3
-

the charge which matters. NH4
+
Zn
2+
HCO3
-

2+ -
Pb OH
What combinations of ions are needed to
make the following compounds?
• Sodium chloride
• Lithium iodide Na+ Cl- Fe3+ Fe3+
• Calcium carbonate
• Sodium hydroxide
balance the charges: 6+ and 6-
• Iron (III) oxide O2- O2- O2-

Ionic bonding works in 3-D, so
ionic compounds form crystal
structures. They are strong
and can form aqueous
solutions. They are good
electrical conductors when
dissolved or molten.

http://en.wikipedia.org/wiki/Iron(III)_oxide

Ionic Bonding
Cations Anions
+1 +2 +3 -3 -2 -1
+ 2+ 3+ 3- 2- -
H Mg Al N O Cl
Practice drawing Lewis dot structures for + 2+ 3- 2- -
Na Fe PO4 CO3 I
these ionic bonds: K
+
Cu
2+
SO4
2-
NO3
-

+ 2+ -
NH4 Zn HCO3
• hydrogen chloride Pb
2+
OH
-

• iron (II) oxide

• potassium iodide

• copper sulphide (CuS)

• potassium nitride

Metallic Bonding
In bonds between metal atoms, electrons
become delocalised and move freely.

This makes them very malleable and
ductile. Freely-moving electrons makes
them very good electrical conductors.

From GCSE Bitesize: http://goo.gl/tJlVP

Animation from:
http://www.drkstreet.com/resources/m
etallic-bonding-animation.swf

The duet and octet rules
Hydrogen and helium follow the duet rule –
two valence electrons. They have a small H H
outer electron shell.

H2 (H-H) H H H H
Single covalent bond shared the line represents
electrons a pair of electrons.

The duet and octet rules
Hydrogen and helium follow the duet rule –
two valence electrons. They have a small H H
outer electron shell.

H2 (H-H) H H H H
Single covalent bond shared the line represents
electrons a pair of electrons.
Other elements follow the octet rule.
They will gain, lose or share electrons
until the outer shell has a full set of 8.
O O
We can work out how bonds will form by
adding up the total number of valence
O2 (O=O)
electrons and distributing them.
O O O O
Two oxygen atoms have a total of 12 valence
electrons. By sharing them in covalent bonds, shared shared
they can make up the 8 needed. electrons electrons
Double covalent bond each line represents a pair of electrons.

Diatomic molecules
These are molecules which are found as pairs of atoms,
H H sharing electrons. They can be elements or compounds.

H2 See if you can draw Lewis dot configurations
for these diatomic molecules.
H H
F F Cl Cl Br Br
O O F2 Cl2 Br
2
O2

O O N I I
NN I2
2

Covalent Bonding
Forms between non-metals.
Atoms share valence electrons in the outer shell.
They do not form large crystals like ionic compounds.
http://www.visionlearning.com/library/m
A single bond is the force between odule_viewer.php?mid=55 (animation)
two atoms which are sharing two electrons, e.g. H-H.
Double bonds are formed when
two atoms share four electrons, such as O=O.

Water is an example of a polar covalent bond.
Oxygen has more protons and pulls the shared
electrons more strongly.
The electrons are not σ-
shared equally.
http://www.allthingsscience.com/video/849/Ionic-

The oxygen side is slightly O and-covalent-bonding-animation

negative and the
hydrogens are
slightly positive. H H σ+
σ+
σ = “slightly”

Only covalently-bonded compounds
can be accurately called ‘molecules’.

Ionic compounds interact in crystals.

Covalent Bonding Non-metals will share electrons
when they bond.

How many electrons does oxygen have in total?

O How many of these are valence electrons?

How about hydrogen?

Draw them on. Draw a Lewis Dot structure for each.
H

when they bond.

Oxygen: 8 electrons, 6 valence electrons.
Hydrogen: 1 electron, 1 valence electron.
O
O H
Oxygen follows the octet rule and needs eight valence
electrons to be stable.

H Hydrogen follows the duet rule and needs two.
It has one already, so will share it with oxygen.

when they bond.

H O
Oxygen follows the octet rule and needs eight valence
electrons to be stable.
H
O
Hydrogen follows the duet rule and needs two.
It has one already, so will share it with oxygen.

Now the hydrogen has a full valence shell…

… but the oxygen is one short.

when they bond.

H
H O
H

Another hydrogen atom can share the final electron
needed to fill the valence shell of oxygen.
H
O
This gives water – H2O!

Polar Bonds Larger atoms exert a greater pull on shared electrons.

Oxygen has more protons than hydrogen.
This means there is a stronger attraction between
the shared electrons and oxygen than there is
with the nucleus of hydrogen.

The result is a polar bond. Electrons are pulled
slightly closer to the oxygen, making it slightly
negatively charged overall. The hydrogen ends up
σ+ slightly positively charged.
σ = “slightly”
This will happen in any covalently-bonded
molecule where there is a big difference in atomic
σ+ numbers. The bigger the difference, the stronger
the effect.
σ-

Hydrogen Bonding
This is really an inter-molecular force
σ- between polar molecules.
It is a dipole-dipole attraction
O involving H-O, H-F or H-N bonds.

Electrons in covalent bonds
can be unevenly shared, Animation from Sumanas:
H H http://goo.gl/rblz1
making the molecule polar.
σ+ σ+
These slight charges will attract opposites,
such as in water and DNA!
hydrogen bond
σ = “slightly” σ-

http://dna.microbiologyguide.com/s/10002/pics/dnabases.gif

Water molecules are attracted to each other with hydrogen bonds.

σ-
O

H H
σ+ σ+

hydrogen bond

The polar nature of water allows it to act as a solvent for ionic solids.
Annotate this model of water dissolving NaCl.

Carbon dioxide

C
C

O O

O
O

Carbon dioxide: double bonds

O C O
C Two double bonds are formed.
These are shorter and stronger
shared O than single bonds.
electrons
shared
electrons
O C O
Bonds and electrons can also be
By forming a double bond with each oxygen represented with these lines.
atom, carbon has shared four more electrons Each line represents two electrons.
in its valence shell and is stable.

Carbon monoxide: triple bonds

C O C
One triple bond is formed. These
are shorter and stronger than
single and double bonds.
The oxygen atom shares four electrons and
the carbon shares two. This gives six shared
electrons – a triple bond. O C
Bonds and electrons can also be
represented with these lines.
Each line represents two electrons.

Van der Waal’s Forces
When non-polar molecules come in very close contact with
each other, an attractive force called Van der Waal’s force can
be created. This is because an induced dipole is created.

It is is a very weak inter-molecular force,
but the cumulative total of Van der Waal’s
forces can be quite strong.

Gecko feet are thought to use VdW’s forces.
They have thousands of tiny hairs called spatulae,
which maximise the surface area for forces to act.

1μm
Read about how geckoes use Van der Waal’s forces here:
http://news.bbc.co.uk/2/hi/science/nature/781611.stm

Assessment: Knowledge and Understanding
MrT will give you two elements and the conclusion of a fictitious student.
Using all of your knowledge from Atoms and Bonding, explain how they will bond.
Analyse and evaluate the student’s conclusion.

Work through these steps:
• Draw atomic structure diagrams of each
• Identify the number of valence electrons
• Draw Lewis dot structures
• State whether they will bond ionically or covalently and why.
• If they bond ionically, explain which will form an anion and which will forma
cation and why.
• Draw diagrams to show how they will bond
• Show the final Lewsis Dot structures and state whether the bonds are single,
double or triple and why.
• If they bond covalently, try to determine if they will form a polar bond and
identify which part will be positive and which negative, and why.

Submit this on a separate piece of paper, along with this worksheet. It will be assessed for
criterion C: Knowledge and Understanding.

A H B C
O O
H
H
O H O D
H H

E F G + H
2-
H H H O

σ-
O

H H
σ+ σ+

hydrogen bond

One World Issues: Group Poster Task
Explain the problem and outline how the use of Explain how the A-bomb worked
the bomb was thought to be a solution. and was used.

Identify the stakeholders. Evaluate and discuss the
Who are all the people or groups who were implications of the bomb.
affected in some way by the use of the bomb?

Discuss the use of the bomb, from multiple perspectives,
for each of these One World issues:
social moral ethical political

environmental economic cultural

This will help you write your own personal
essay on One World in Chemistry…

How do we use these radioisotopes?
Quick research and presentation:
- What is it and how is it an isotope?
- What is it used for?
- HOW is it used for this purpose?

Uranium-235
Cesium-137

Cobalt-60

Criterion A: One World “The role of radioisotopes in Science.”
Level Level descriptor
0 The student does not reach a standard described by any of the descriptors below.

1–2 The student states how science is applied and how it may be used to address a specific problem or issue in a local or global context.
The student states the effectiveness of science and its application in solving the problem or issue.

3–4 The student describes how science is applied and how it may be used to address a specific problem or issue in a local or global context.
The student describes the effectiveness of science and its application in solving the problem or issue.
The student describes the implications of the use and application of science interacting with at least one of the following factors: moral,
ethical, social, economic, political, cultural and environmental.

5–6 The student explains how science is applied and how it may be used to address a specific problem or issue in a local or global context.
The student discusses the effectiveness of science and its application in solving the problem or issue.
The student discusses and evaluates the implications of the use and application of science interacting with at least two of the following
factors: moral, ethical, social, economic, political, cultural and environmental.

Criterion B: Communication in Science
Level Level descriptor
0 The student does not reach a standard described by any of the descriptors below.

1–2 The student uses a limited range of scientific language correctly.
The student communicates scientific information with limited effectiveness.
When appropriate to the task, the student makes little attempt to document sources of information.

3–4 The student uses some scientific language correctly.
The student communicates scientific information with some effectiveness.
When appropriate to the task, the student partially documents sources of information.

5–6 The student uses sufficient scientific language correctly.
The student communicates scientific information effectively.
When appropriate to the task, the student fully documents sources of information correctly.

Common ions:
Cations Anions
+1 +2 +3 -3 -2 -1
+ 2+ 3+ 3- 2- -
H Mg Al N O Cl
+ 2+ 3- 2- -
Na Fe PO4 CO3 I
+ 2+ 2- -
K Cu SO4 NO3
+ 2+ -
NH4 Zn HCO3
2+ -
Pb OH
Positively charged ions are cations. Negatively charged ions are anions.
(Think: cats make old ladies happy) (Think: A Negative ION)

What’s the difference between the ions in purple and those in black?
Compare the elemental ions to the periodic table. Can you describe a trend?
Can you explain why the elements above form these specific ions?

What do you think?

Ideas based on
Concept Cartoons:
http://www.conceptcartoons.com

Clipart people from: http://www.clker.com/search/krug/1

South-West A South-West B
South-East A South-East B
North-East A North-East B
North-West A North-West B
MrT’s Chemistry Shop

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