THE CHEMICAL FOUNDATIONS OF LIFE

1
CHAPTER 2

• THE CHEMICAL FOUNDATIONS OF LIFE
• Alchemy and Chemistry

2
WHAT IS MATTER?

• CHEMISTRY
• MATTER
• CHEMICAL REACTIONS
• ATOMS
• NUCLEAR REACTIONS
• MOLECULE
• COMPOUNDS

3
What Is Chemistry?

• metallurgy

4
WHAT DETERMINES THE PROPERTIES OF AN ATOM?

• MASS

5
What Are Atoms Made Of?

• Calculate molecular weight.

6
What Is the Internal Structure of an Atom?

• NUCLEUS
• PROTONS
• NEUTRONS
• ELECTRONS

7
ISOTOPES

• RADIOACTIVE ISOTOPES

• HALF-LIFE

8
What Does Radioactivity Do to Living Organisms?

• free radicals

9
Where Are the Electrons in an Atom?

• ENERGY
• SHELLS

• TWO RULES ON DISTRIBUTION
• PRACTICE DRAWING COMMON ELEMENTS

10
WHAT HOLDS MOLECULES TOGETHER?

• Eight electrons to an energy level
• 1,2, or 3 electrons may be given up
• 4 electrons will usually be shared
• 5,6, or 7 electrons may gain more
• Inert elements have 8 electrons and are unreactive

11
Covalent and ionic Bonds Are the Strong
Interactions Among Atoms

• covalent bonds
• ionic bonds
• ions

12
Atoms Share Electrons in Covalent Bonds

• SPONCH
• Organic compounds contain carbon
• Double covalent bonds
• Triple covalent bonds

13
What Determines the Shape of a Molecule?

• Bonds give a 3-D structure.
• Fig. 2-8

14
How are radioisotopes useful?

• Give examples.

15
Atoms Lose and Gain Electrons in Ionic Bonds

• Ions have a gain or loss of electrons to form
  or - charges.
• Opposite charges attract.
• Fig. 2-9

16
Atoms Have Different Tendencies To Gain or Lose
Electrons

• Electronegativitity - the tendency to gain
  electrons

• polar- has uneven charge distribution

• nonpolar-has uniform charge distribution

17
Weak Interactions Also Hold Atoms Together

• aqueous (watery) environment

18
Hydrophobic Molecules Cling Together in an
Aqueous Solution

• Hydrophilic
• Hydrophobic
• Give examples.

19
Van der Waals Attractions Reinforce Hydrophobic
Interactions
20
Hydrogen Bonds Are Weak But Important

• Hydrogen bonds in water, protein, and DNA. Fig.
  2-12

21
Water Is Denser as a Liquid Than as a Solid

• Table 2-2
• Compare water to alcohol and oil

22
Water Absorbs More Heat Than Most Substances

• Heat capacity

• stores heat

• cools coasts and the body

23
Water Molecules Cling to One Another

• Cohesion

• Surface tension
• Give examples.

24
Water Molecules Cling to Many Other Substances

• Adhesion

• Capillary action
• Give examples.

25
Water Is a Powerful Solvent

• Solvent

• Solute

• Amphipathic - contain both hydrophilic and
  hydrophobic regions
• Examples- detergent and mayonnaise
• Fig. 2-18

26
Water Participates in Many Biochemical Reactions

• Planet Water

27
Water Molecules Continually Split into Hydrogen
Ions and Hydroxide Ions

• Hydroxide ion (OH-)
• Hydronium ion (H3O)
• Study equations.

28
pH Scale

• pH power of the hydrogen
• pH scale 1 - 14
• logarithm to the base 10
• A pH of 2 is 100 X as strong as a pH of 4
• each number is a 10 fold difference

• acid - a pH of 0-6.99
• Contains more hydrogen than hydroxide ions
• pH 7 H OH H2O

• base - a pH over 7 - 14
• Contains more hydroxide than hydrogen ions
• Fig. 2-20

29
Life At Low pH

• Box 2-2

30
Why Is pH Important to Organisms?

• Discuss examples.

31
Buffers How Do Organisms Resist Changes in pH?

• Buffers neutralize acids and bases.
• Carbonic acid and bicarbonate are two important
  buffers of the body.
• Body pH should be 7.35-7.45 or problems will
  occur.
• Acids and bases combine to form salts and water.
• Acids buffer bases - bases buffer acids