1. Physical Properties of Water

2. * Water statistics (why understanding it is important!)
Covers 75% of Earth’s surface
97% salt water
3% freshwater
2% (of Total) in ice caps and glaciers
1% in lakes, underground, or in atmosphere (usable by humans)
Makes up 70% of the human body
92% of blood plasma
80% of muscle tissues
60% of red blood cells

3. Physical properties Water:
Is clear, colorless, odorless, and tasteless
* Colors, tastes and odors are caused by substances dissolved in the water.
Boils at 100°C (212 F)
Freezes at 0°C (32 F)
Density = 1.0 g/mL (at 4°C)
Water is a Polar Molecule

4. Polarity of Water
In a water molecule two hydrogen atoms form covalent bonds with one oxygen atom.
These covalent bonds cause the oxygen atom to be slightly negatively charged and the hydrogen atoms to be slightly positively charged
There are two oppositely charged ends so it is said to be polar
2 corners are orbitals with unshared electrons and a weak negative charge
2 are occupied by hydrogen atoms that have polar covalent bonds

5. Water has a variety of unusual properties because of attractions between these polar molecules.
The slightly negative regions of one molecule are attracted to the slightly positive regions of nearby molecules, forming a hydrogen bond.
Each water molecule can form hydrogen bonds with up to four neighbors.
Fig. 3.1
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

6. Adhesion – water sticking to other things
The adhesion of water leads to two important properties:
Water as a “universal” solvent
Water only dissolves polar molecules
Ex: Salt
Sugar
Carbon Dioxide
Oxygen
Capillary action
Water will make hydrogen bonds with other surfaces such as glass, soil, plant tissues, and cotton.
Making it able to “climb” objects against the forces of gravity
Check this out
Adhesion is also what causes water to bead on plants and other materials

7. Cohesion – water molecules sticking to other water molecules
video
The cohesion of water molecules leads to two important properties:
Surface Tension – the attraction between water molecules at the surface of the liquid
Water has a greater surface tension than most other liquids because hydrogen bonds among surface water molecules resist stretching or breaking the surface
Water behaves as if covered by an invisible film.
High Specific Heat – it takes a lot of energy to warm up water and it takes a very long time for warm water to cool off
Due to the fact that its hydrogen bonds are constantly breaking and reforming
Video of water properties

8. “Water vapor forms a kind of global ‘blanket’ which helps to keep the earth warm. Heat radiated from the sun-warmed surface of the earth is
absorbed and held
by the vapor.” 1