Biology 101 - Chapter 3: The Solvent of Life

Chemical Formula of Water

H2O, 2 hydrogen atoms, 1 Oxygen atom, has a polar covalent bond

Polar Covalent Bond

unequal sharing of e-, e- spends more time closer to O

Polar molecule

uneven charge distribution

Why is water the universal solvent?

Because it is a polar molecule.

What percentage of living organisms is made up of water?

70%-95%

How many water molecules are pictured?

5

Where in this photo is a polar covalent bond?

Between hydrogen and oxygen

Where in this photo is a hydrogen bond?

Between the 8- charge and 8+ charge

What atom in a water molecule is more electronegative?

Oxygen

What are the 4 emergent properties of water?

1. cohesive behavior

2. moderation of temperature

3. ice floats on liquid water

4. water is the solvent of life

What type of bond holds water molecules together, creating cohesive behavior?

Hydrogen bonds

What is surface tension?

measure of how difficult it is to stretch or break surface of liquid.

How does water moderate temperature?

• water absorbs heat and hydrogen bonds break

• water releases heat and hydrogen bonds form

Why is it important that water moderates temperature?

• creates an environment suitable for life

• moderates coastal air temperatures