1. Review of Basic Chemistry
Chapter 2: Water and Carbon: The Chemical Basis of Life
Life requires about 25 elements
carbon (C) oxygen (O) hydrogen (H) nitrogen (N)

2. Chapter 2: Water and Carbon: The Chemical Basis of Life
Atoms and molecules:
*Atomic number
*Mass number
The energy levels of electrons:
*electrons vary in energy
Energy
Potential energy

3. *chemical behavior due to electrons
Chapter 2: Water and Carbon: The Chemical Basis of Life
Energy levels of electrons
Electron configuration and chemical properties:
*chemical behavior due to electrons

4. Chapter 2: Water and Carbon: The Chemical Basis of Life
Atoms combine by chemical bonding to form molecules
*Chemical behavior depends on valence electrons
*Covalent bond
Examples:
Covalent bond
Double Covalent bond

5. Chapter 2: Water and Carbon: The Chemical Basis of Life
Atoms combine by chemical bonding to form molecules:
Another example:
Compound
*electronegativity
nonpolar covalent bond
polar covalent bond
Example:
H2O - water

6. Chapter 2: Water and Carbon: The Chemical Basis of Life
Atoms combine by chemical bonding to form molecules:
*ionic bonds
*ion
*cation
*anion
ionic compounds or salts

7. Chapter 2: Water and Carbon: The Chemical Basis of Life
Atoms combine by chemical bonding to form molecules:
*bonding between molecules
Hydrogen bonds:

8. Chapter 2: Water and Carbon: The Chemical Basis of Life
Water: what’s the big deal?
Polarity of water:
*Hydrogen bonding
*Cohesion
water transport in plants
adhesion

9. Chapter 2: Water and Carbon: The Chemical Basis of Life
Water is the solvent of life
*solution
*solvent *solute *aqueous solution
*polar and ionic molecules can be dissolved in water

10. Chapter 2: Water and Carbon: The Chemical Basis of Life
Hydrophilic and hydrophobic substances
*hydrophilic
*hydrophobic
The dissociation of water molecules
H2O H+ + OH-
Acids and bases
*acid
*base

11. Chapter 2: Water and Carbon: The Chemical Basis of Life
The pH scale