properties of water.ppt for grade 9 high school

1. 1. What does the atom consist of?
A. electrons, protons, and alpha particles
B. neutrons and protons
C. electrons, protons, and neutrons
D. elements, protons, and electrons
2.The nucleus of one atom contains 12 pro- tons and 12
neutrons, while the nucleus of another atom contains 12
protons and 16 neutrons. What are the atoms?
A. chromium atoms
B. two different elements
C. two isotopes of an element
D. negatively charged
3.What are two atoms that have the same number of protons
called but different neutrons called?
A. metals
B. nonmetals
C. isotopes
D. metalloids
Check point
4.An ionic bond is the attraction between:
A. oppositely charged ions
B. similarly charged ions
C. neutral ions
D. neutral atoms
5.A covalent bond in which electrons are shared unequally is:
A. polar
B. a double bond
C. ionic
D. polyatomic
6.What is a compound?
A. a mixture of chemicals and elements
B. a combination of two or more elements
C. anything that has mass and occupies space
D. the building block of matter

2. Isotopes are atoms of one element that vary only in the number of
neutrons in the nucleus. In nature, an element occurs as a mixture of
isotopes. Chemically, all isotopes of the same element are identical because
they have the same number of electrons in the same configuration. For
example: carbon-12 and carbon-14 are isotopes of each other and are
chemically identical. Some isotopes, like carbon-14, are radioactive and
decay at a known rate called the half-life. Knowing the half-life enables us
to measure accurately the age of fossils or to estimate the age of the earth, a
process known as radiometric dating. Radioisotopes (radioactive isotopes)
are useful in many other ways. For example, radioactive iodine (I-131) can
be used both to diagnose and to treat certain diseases of the thyroid gland.
Additionally, a tracer such as radioactive carbon can be incorporated into a
molecule and used to trace the path of carbon dioxide in a metabolic
pathway.

3. Why do we have these phenomena ?

4. What I know
about Water
What I Learned
about Water
What I want to
learn about
water

5. Properties of Water
Covalent bonding
Polar covalent bond – unequal sharing of
electrons
A great example of a molecule with polar
covalent bonds is water. Why is water
considered polar?
What is a partial positive and partial
negative charge?

6. Properties of Water
Covalent bonding vs. Hydrogen bonding
Covalent Bond
Hydrogen Bond

7. Properties of Water
Water is the solvent of Life!
Solute – substance dissolved in a
solvent to form a solution
Solvent – fluid that dissolves solutes
Example: Ice Tea – water is the
solvent and tea and sugar the solutes
Universal Solvent

8. Properties of Water
1. ___________ = water attracted to other water
molecules because of polar properties
2.____________= water attracted to other materials
3.___________= water is pulled together creating
the smallest surface area possible
Cohesion, Adhesion and Surface Tension

10. papers

11.  Cohesion (cohesive) – sticking together of
two like molecules
2 water molecules are cohesive due to the
hydrogen bonds
 Adhesion (adhesive) – sticking together of
two unlike molecules
Ex: A water molecule being attracted to a sugar
molecule (Like making Kool-aid)

12.  Cohesion among water
molecules causes them
to pull one another
upward against gravity
 Adhesion contributes
too, as water adheres
to the wall of the
vessels, so it can travel
upward
How does water get to the top of plants?
Cohesion & Adhesion

13.  1. Water moves up a tall tree from the roots to the leaves without
the
 expenditure of energy by what is referred to as
transpirationalpull
 cohesion tension. As one molecule of water is lost from the
 leaf by transpiration, another molecule is drawn in at the roots.
 2. Capillary action results from the combined forces of cohesion
and
 adhesion, attraction of unlike substances.

14. Some insects are able to walk across water. How do
the properties of water explain their ability?

15. 3. Surface Tension
 Surface tension- a measure of the force
necessary to stretch or break the surface of
a liquid
Hydrogen bonds between water molecules at
surface of water resist breaking creating an
“invisible film”
This allows some insects to walk/run on water

16. 4. Heat Capacity
 Specific Heat - amount of heat that
must be absorbed or lost before it
actually changes temperature
Water has a high specific heat
Water can absorb or release large
amounts of heat with only a slight change
in its own temperature.
 Ex: Water takes a long time to boil

17. Practice
1. Which of the following describes a hydrogen
bond?
a. the bond between two hydrogen atoms
within a molecule of water
b. the bond between hydrogen in one water
molecule and another hydrogen in a
different water molecule
c. the bond between hydrogen and oxygen
within a molecule of water
d. the bond between hydrogen in one water
molecule and oxygen in a different water
molecule

18. Properties of Water
Density
Water is less dense as a solid! This is because the
hydrogen bonds are stable in ice – each molecule of
water is bound to four of its neighbors.
Solid – water molecules
are bonded together –
space between fixed
Liquid – water molecules
are constantly bonding
and rebonding – space is
always changing

19. how can the fish live under ice‫؟‬
Why didn’t the water freeze ?

20. 1.Water has a high surface
tension. What property of water
allows an insect to walk on
water?
a. Adhesion
b. Cohesion
c. Ionic Bonds
d. Nonpolar Covalent Bonds
2. Which property of water
helps to explain that it
takes a bit of time for a
pot of water to boil?
a. adhesion
b. density
c. specific heat
d. universal solvent

21. HYDROPHOBIC AND HYDROPHILIC SUBSTANCES
Hydrophilic means “water loving.” Substances that are polar such as
hydrochloric acid (HCl), or that carry a charge like the hydronium ion
(H3O+), or that are ionic like table salt (NaCl) will dissolve in water. Since
so many substances dissolve in water, water is known as the “universal
solvent.”
Hydrophobic means “water hating” and applies to nonpolar substances,
which are miscible with or will dissolve in lipids. Salad dressing separates
upon standing because oil (hydrophobic) and vinegar (hydrophilic, acetic
acid solution in water) are not miscible.

22. 1.Water Has A High Specific Heat.
Specific heat is the amount of heat that must be absorbed in order for 1 gram of
a substance to change its temperature 1° Celsius. This means that large bodies of
water, like oceans, absorb a lot of heat and resist changes in temperature. As a
result, they provide a stable environment for the organisms that live in them.
Also, coastal areas exhibit relatively little temperature change because the
oceans moderate their climates.
2.Water Has A High Heat Of Vaporization.
This means that a relatively great amount of heat is needed to evaporate water.
As a result, evaporation of sweat significantly cools the body surface.
3.Water Has High Adhesion Properties.
Adhesion is the clinging of one substance to another, and it plays an important
role in plant survival. Forces of adhesion contribute to capillary action, which
helps water flow up from the roots of a plant to the leaves.

23. 4.Water Is The Universal Solvent.
Because water is a highly polar molecule, it dissolves all polar and ionic substances.
5.Water Exhibits Strong Cohesion Tension.
This means that molecules of water tend to stick to each other. This results in several
biological phenomena. Water moves up a tall tree from the roots to the leaves
without the expenditure of energy by what is referred to as transpirational-pull
cohesion tension. It also results in surface tension
that allows insects to walk on water without breaking the surface.
6.Ice Floats Because It Is Less Dense Than Water.
In a deep body of water, floating ice insulates the liquid water below it, allowing life
to exist beneath the frozen surface during cold seasons. The fact that ice covers the
surface of water in a lake in the cold months and melts in the spring results in a
stratification of the lake during the winter and considerable mixing in the spring. In
the spring, surface ice melts, becomes denser water, and sinks to the bottom of the
lake, causing water to circulate throughout the lake. Oxygen from the surface is
returned to the depths, and nutrients released by the activities of bottom-dwelling
bacteria are carried to the upper layers of the lake. This cycling of the nutrients in
the lake is known as the spring overturn and is necessary to the health of a lake.

26. Acids and Bases
Strength compared using pH scale
Ranges from 0 – 14
Logarithmic Scale (gets 10x bigger/smaller)
Acid – donates H+ when added to aqueous solutions
Ranges from pH 0-6.9
Base – breaks up into hydroxide (OH-) ions and
another compound when placed in an aqueous
solution
Ranges from pH 7.1 – 14
Distilled water is pH 7.0 or neutral. Why?
H2O H+ + OH-

27. pH is a measure of the acidity and alkalinity of a solution. Anything with a
pH of less than 7 is an acid, and anything with a pH value greater than 7 is
alkaline or basic. A pH of 7 is neutral. The value of the pH is the negative
log of the hydrogen ion concentration in moles per liter. See Table 2.1,
which shows pH values compared with molarity.
A substance with a pH of 3 has 1.0 × 10–3 or 0.001 mole per
liter of
hydrogen ions in solution, while a substance of pH 4 has a H+
concentrationof 1.0 × 10–4 or 0.0001 mole per liter of hydrogen
ions in solution. Therefore, a solution of pH 3 is 10 times more
acidic than a solution with a pH of 4. A solution with a pH of 6 is
1,000 times more acidic than a solution with a pH of 9;