1. Water is a polar molecule made up of oxygen and hydrogen atoms, with the oxygen side having a slight negative charge and the hydrogen sides having a slight positive charge. 2. This polarity allows water molecules to form hydrogen bonds with other water molecules, giving water its unique properties. Water is able to dissolve many other polar substances for this reason. 3. The hydrogen bonding between water molecules also gives water properties like high surface tension and the ability to exist as a liquid at temperatures higher than zero degrees Celsius. This hydrogen bonding is important for life.

1. Water and Solutions

2. Water and Solutions
1. Water is the MOST important
compound in living organisms!
2. It accounts for approximately
70% of a cell’s mass.
3. It covers about 70% of the
world’s surface

3. 1. Water is a polar molecule
2. The bonds in a water molecule are
called polar covalent bonds
3. It is this polarity that gives it some of
it’s unique characteristics
What makes water special?

4. 4. Recall that covalent bonds involve
atoms sharing electrons.
5. In the care of a “polar covalent
bond” the electrons are not shared
equally.
6. Electrons are more strongly
attracted to the oxygen than the
hydrogen.

5. 7. This makes the
oxygen side of the
molecule slightly
negative.
8. It also makes the
hydrogen side of
the molecule
slightly positive.
“Polar opposites!”
Draw this

6. 9. Polarity is the property of
having two opposite poles
(or ends).
9. Water is similar to a
magnet. When the two
oppositely charged sides
of a water molecule are
brought together they
want to “stick” together
the way magnets do.Opposites attract!

7. 11. When a water molecule “sticks” to other
water molecules it forms weak hydrogen
bonds molecules around it.
-This stickiness creates surface tension in
water.

8. 12. Hydrogen bonds between water
molecules hold them together
13. Hydrogen bonds are weak
interactions

10. Water’s Properties
1. Water’s properties can be attributed to
the fact that it is a polar molecule that
forms hydrogen bonds with other
water molecules around it.

11. 2. Some of these special
properties include…
• Water’s ability to dissolve
polar substances
• Water is the “universal
solvent”
• Remember that like
dissolves like.
Therefore, water
dissolves other polar
substances.
• Water cannot, however
dissolve non-polar
substances such as oil.

12. • Liquid water is most
dense at 4 degrees
C. Ice is less dense
than liquid water.
• Nutrients in water mix
due to changes in
water density during
spring and fall. Also,
ice acts like an
insulator in the winter.

13. • Water is adhesive
• It forms hydrogen bonds with
molecules on other surfaces

14. • Water is cohesive
• Water sticks to itself
That’s why a belly-smacker hurts!

15. Mixtures with Water
1. Mixture = combination of two or more
substances where each substance retains its
own characteristics and properties
2. Homogeneous mixtures = same throughout
(ex. Air)

16. 3. Solution is another name of
homogeneous mixture
a. solvent = dissolver
b. solute = being dissolved
• Ex. Identify the solvent and the solute
in chocolate milk.

17. 4. Heterogeneous mixtures = appears
different throughout
• ex. This cup of grains