Chemistry of Life

1. Chemistry of Life

2. Molecules: • 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

3. Matter • Matter- • Anything that takes up space and has mass • Composed of chemical elements Human Recipe:

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

5. Atom- smallest unit of matter • If an atom loses or gains an electron it becomes an Ion. • Electron arrangement gives the atom its chemical properties

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

7. Covalent & ionic Bonding • Electrons are shared among atoms • Molecules are held together by these • Can be polar or non-polar • Electrons are transferred • Holds Ions together

8. Covalent Bonding • Unequal charges among atoms • Charges are kept equal among atoms Polar Non- Polar

9. Hydrogen bonds are weak bonds important in the chemistry of life (–) (–) O H H (+) (+) http://www.youtube.com/watch?v=CT4pURpXkbY

10. Hydrogen bond

11. Properties of Water • 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

12. Evaporative Cooling • 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

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

14. Water is the solvent of life solution = solvent (dissolving agent) + solute Universal solvent Salt crystal Ion in solution http://www.youtube.com/watch?v=QH1yphfgfFI

15. pH scale 0 1 The chemistry of life is sensitive to acidic and basic conditions Battery acid Lemon juice, gastric juice 2 3 Grapefruit juice, soft drink, vinegar, beer Increasingly ACIDIC (Higher concentration of H+) Acidic solution 4 Tomato juice 5 Rain water 6 Human urine Saliva NEUTRAL [H+]=OH–] 7 Pure water Human blood, tears 8 Seawater Neutral solution 9 10 Increasingly BASIC (Lower concentration of H+) Milk of magnesia 11 Household ammonia 12 Household bleach 13 Oven cleaner Basic solution 14

16. Acidic solution Basic solution Neutral solution

17. StronglyA B C D E Strongly DisagreeAgree 0 Biology and Society • 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?

18. StronglyA B C D E Strongly DisagreeAgree 0 Biology and Society • 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?