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CHAPTER 2
• THE CHEMICAL FOUNDATIONS OF
LIFE
• Alchemy and Chemistry
WHAT IS MATTER?
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CHEMISTRY
MATTER
CHEMICAL REACTIONS
ATOMS
NUCLEAR REACTIONS
MOLECULE
COMPOUNDS
What Is Chemistry?
metallurgy
WHAT DETERMINES THE
PROPERTIES OF AN ATOM?
MASS
What Are Atoms Made Of?
Calculate molecular weight.
What Is the Internal Structure of
an Atom?
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NUCLEUS
PROTONS
NEUTRONS
ELECTRONS
ISOTOPES
• RADIOACTIVE ISOTOPES
• HALF-LIFE
What Does Radioactivity Do to
Living Organisms?
free radicals
Where Are the Electrons in an
Atom?
• ENERGY
• SHELLS
• TWO RULES ON DISTRIBUTION
• PRACTICE DRAWING COMMON ELEMENTS
WHAT HOLDS MOLECULES
TOGETHER?
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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
Covalent and ionic Bonds Are the
Strong Interactions Among
Atoms
covalent bonds
ionic bonds
ions
Atoms Share Electrons in
Covalent Bonds
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SPONCH
Organic compounds contain carbon
Double covalent bonds
Triple covalent bonds
What Determines the Shape of a
Molecule?
Bonds give a 3-D structure.
Fig. 2-8
How are radioisotopes useful?
Give examples.
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
Atoms Have Different
Tendencies To Gain or Lose
Electrons
• polar- has uneven charge
• Electronegativitity the tendency to gain
electrons
distribution
• nonpolar-has uniform
charge distribution
Weak Interactions Also Hold
Atoms Together
aqueous (watery) environment
Hydrophobic Molecules Cling
Together in an Aqueous Solution
Hydrophilic
Hydrophobic
Give examples.
Van der Waals Attractions
Reinforce Hydrophobic
Interactions
Hydrogen Bonds Are Weak But
Important
Hydrogen bonds in water, protein,
and DNA. Fig. 2-12
Water Is Denser as a Liquid Than
as a Solid
• Table 2-2
• Compare water to alcohol and oil
Water Absorbs More Heat Than
Most Substances
• Heat capacity
• stores heat
• cools coasts and the body
Water Molecules Cling to One
Another
• Cohesion
• Surface tension
• Give examples.
Water Molecules Cling to Many
Other Substances
• Adhesion
• Capillary action
• Give examples.
Water Is a Powerful Solvent
• Solvent
• Solute
• Amphipathic - contain both hydrophilic and
hydrophobic regions
• Examples- detergent and mayonnaise
• Fig. 2-18
Water Participates in Many
Biochemical Reactions
Planet Water
Water Molecules Continually
Split into Hydrogen Ions and
Hydroxide Ions
Hydroxide ion (OH-)
Hydronium ion (H3O+)
Study equations.
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
Life At Low pH
Box 2-2
Why Is pH Important to
Organisms?
Discuss examples.
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