 All living and nonliving things are made of molecules.  Molecules are made up of atoms  So we must understand atoms to understand the chemistry of life

 Matter-  Anything that takes up space and has mass  Composed of chemical elements Human Recipe:

 Compounds- substance of two or more elements combined in a fixed ratio Sodium (Na) Chlorine(Cl) Table Salt (NaCl) + =

 If an atom loses or gains an electron it becomes an Ion.  Electron arrangement gives the atom its chemical properties

 Atoms with the same amount of protons and electrons, but a different amount of neutrons are called Isotopes.

Electrons are shared among atoms Molecules are held together by these Can be polar or non-polar Electrons are transferred Holds Ions together

PolarNon- Polar  Unequal charges among atoms  Charges are kept equal among atoms

(–) O HH (+) Hydrogen bonds are weak bonds important in the chemistry of life

Hydrogen bond

 Adhesion- – water can stick to other molecules  Causes the meniscus in a test tube  Cohesion-  water sticks to other water molecules  Because of hydrogen bonding  Causes high surface tension- difficulty to break the surface of a liquid

 Water is highly resistant to heat  Heat is absorbed when bonds form  Heat is released when bonds break  Evaporative Cooling- water molecules of high energy leave  Ex: Sweating

Liquid water Hydrogen bonds constantly break and re-form Ice Hydrogen bonds are stable Hydrogen bond Ice is less dense than liquid water

Ion in solution Salt crystal Water is the solvent of life solution = solvent (dissolving agent) + solute Universal solvent

Acidic solution pH scale Battery acid Lemon juice, gastric juice Grapefruit juice, soft drink, vinegar, beer Tomato juice Rain water Human urine Saliva Pure water 6 7 Human blood, tears Seawater Milk of magnesia Household ammonia Household bleach Oven cleaner Neutral solution Basic solution NEUTRAL [H + ]=OH – ] Increasingly ACIDIC (Higher concentration of H + ) 14 Increasingly BASIC (Lower concentration of H + ) The chemistry of life is sensitive to acidic and basic conditions

Acidic solution Neutral solution Basic solution

 One of the authors of your text once overheard the following:  “It’s paranoid and ignorant to worry about industry or agriculture contaminating the environment with their chemical wastes. After all, this stuff is just made of the same atoms that were already present in our environment anyway.”  What do you think of this statement? Why? Disagree Agree Strongly A B C D E Strongly

 Too little iodine in the diet can lead to goiter—the condition afflicting this person. Goiter is not common in developing countries because iodine is added to salt and other foods.  Do you think that adding trace elements to food items is good public policy? Why? Disagree Agree Strongly A B C D E Strongly