1. One substance all living things require
Water
One substance all living things require
Unique properties due to polar shape
Polar = opposite charges at opposite ends of molecule
like a little magnet
Attracts to opposite charges
3.1 Water pp
What strange things have you noticed about water?

2. The abundance of water is the main reason the Earth is habitable
3.1 Water pp
Most cells are surrounded by water, and cells themselves are about 70–95% water
The abundance of water is the main reason the Earth is habitable
Overview: The Molecule That Supports All of Life

3. Fig. 3-1
Figure 3.1 Why does the abundance of water allow life to exist on the planet Earth?

4. Cohesion = water sticking to other water molecules
3.1 Water pp
Hydrogen Bonding = weak attractive force between positive and negative ends of a water molecule.
Water is “sticky”
Cohesion = water sticking to other water molecules
Adhesion = water sticking to other substances
Water on skin
Capillary action

5. Fig. 3-4
Figure 3.4 Walking on water

6. Hydrogen bond H O H  –  +  –  +  –  +  –  + —— —— Fig. 3-2
Figure 3.2 Hydrogen bonds between water molecules
 –
 +

7. Hydrogen bonds are stable Liquid water
Fig. 3-6
Hydrogen
bond
Ice
Hydrogen bonds are stable
Figure 3.6 Ice: crystalline structure and floating barrier
Liquid water
Hydrogen bonds break and re-form

8. Water is very good at absorbing heat energy.
3.1 Water pp
Water is very good at absorbing heat energy.
Do you feel hotter or cooler around water?

9. San Bernardino Burbank Santa Barbara 73° 100° 90° Riverside 96°
Fig. 3-5
San Bernardino
100°
Burbank
90°
Santa Barbara 73°
Riverside 96°
Los Angeles
(Airport) 75°
Santa Ana
84°
Palm Springs
106°
70s (°F)
80s
Pacific Ocean
90s
100s
Figure 3.5 The effect of a large body of water on climate
San Diego 72°
40 miles