Water is a polar molecule with slightly positively and negatively charged ends, allowing it to form hydrogen bonds between molecules. This polarity gives water properties of adhesion, sticking to other substances, and cohesion, sticking to other water molecules. Water has relatively low viscosity and density compared to other liquids, with density highest at 4°C and lower in seawater due to salt content. Its solid form, ice, floats due to having a less dense crystalline structure. Water also has a high specific heat capacity, requiring a lot of energy to change its temperature, which allows oceans to act as a heat buffer for the planet.

1. Chemical Properties of Seawater

2. Water is a Polar Molecule
Being a “Polar
Molecule”
means that
one end of
the molecule
is slightly
negatively
charged and
the other end
is slightly
more
positively
charged

3. Water has Hydrogen Bonding
This refers to the
type of attraction
seen in this polar
molecule: the
negative oxygen
end of one water
molecule being
attracted to the
positive
hydrogen ends of
another water
molecule

4. Water demonstrates Adhesion & Cohesion
Since water is polar (has oppositely charged ends) it has a tendency to be
attracted to other polar and non-polar molecules
Adhesion – hint: think of Adhesive Tape-we say it is “adhesive” when we
use it to stick a piece of paper to our classroom door, or a person to a wall, for
example
An example of water’s adhesiveness:
when it adheres to and
climbs up a glass forming a meniscus

5. Water demonstrates Adhesion & Cohesion, cont.
Cohesion – hint: think of a team who works well together-we say they are a “cohesive” group
when they stick together to make a great play, for example
An example of water’s cohesiveness: when one water molecule sticks to another water
molecule to bubble over your glass without spilling (a handy trick of water’s that we call surface
tension – the tendency of the top of a liquid to resist external forces)

6. Water has Relatively Low Viscosity
Viscosity is the measure of a fluid’s resistance to flow – water flows
relatively easily (less easily than a gas, but more easily than many other
fluids)
What might influence viscosity?
-changes in temperature
-changes in salinity
-changes in pressure

7. Water has a specific Density
Density is mass/volume
A density less than one means something is able to float
in water
Water is most dense at 4⁰C
What might influence density of seawater?
-Changes in temperature
-Changes in salinity
-Changes in pressure
Q: Which is more dense, seawater or freshwater? Why?

8. Solid vs. Liquid
When water is a
liquid, its polar
molecules are
constantly moving
and bonds are
loose.
When water is a solid,
its polar molecules
are tightly bonded
and form a solid
lattice
This lattice is less
dense and so solid
water (ice) floats.

9. Water has a specific Heat Capacity
Heat capacity is the amount of
energy required to change the
temperature of the water by a
given amount
Important: The ocean is a “heat
buffer”, meaning that it takes a
REALLY long time to heat or
cool the world’s oceans. They
are really BIG so they hold
whatever heat they do have for
a LONG, LONG time…. Why?
Water’s polarity and its
hydrogen bonds mean it takes a
LOT of energy to change the
temperature, even by 1⁰

10. Water has a specific Heat Capacity
Heat capacity is the amount of
energy required to change the
temperature of the water by a
given amount
Important: The ocean is a “heat
buffer”, meaning that it takes a
REALLY long time to heat or
cool the world’s oceans. They
are really BIG so they hold
whatever heat they do have for
a LONG, LONG time…. Why?
Water’s polarity and its
hydrogen bonds mean it takes a
LOT of energy to change the
temperature, even by 1⁰