1. The Chemistry of Life
Unit 3
Chapter 6

2. Atom Proton: positively charged particles Neutron: no charge particles
Electron: negatively charged particles
Nucleus: area of the atom where protons and neutrons are found
Electron cloud: area of the atom where electrons are found

3. Periodic table of elements
Element: substance that cannot be broken down to any simpler chemical substance

4. Compound
Chemical substance made up or two or more atoms of different elements
Must be chemically combined
Ex: table salt (NaCl)

5. Covalent bond: shared electrons between two atoms
Molecules: group of two or more atoms joined covalently

6. How covalent bonds form
Click on image to play video.

7. Ionic bond: transferred electrons between two atoms

8. How ionic bonds are formed
Click on image to play video.

9. Chemical reactions Process in which substances undergo change
A + B  C + D
A and B are reactants.
 means yields.
C and D are products.

10. Mixture
combination of substances where the individual substances retain their original characteristics

11. Solution
one or more substances (solute) is distributed evenly throughout another substance (solvent)
                                 

12. pH
measures the concentration of H+ (protons) in a solution

13. Acid vs. Base Acid: readily forms H+ when in water
pH < 7
Ex: stomach juices
Base: readily forms OH- when in water
pH > 7
Ex: urine
Neutral pH = 7
Ex: blood

14. Properties of water: cohesion
Polarity: unequally shared electrons so that the molecule has unequal charge distribution
Oxygen pulls on electrons more than hydrogen, where oxygen becomes more negative hydrogen becomes more positive
Polar covalent bonds lead to the cohesion property of water where water molecules are attracted to other water molecules.

15. Cohesion and hydrogen bonds

16. Water resists temperature change.
The bonds between oxygen and hydrogen can absorb a large amount of heat energy before they break.
Therefore, aqueous environments (ex: lakes, oceans) where there may be great changes in temperature, organisms can still survive.

17. Water expands when it freezes.
Frozen water (ice) is less dense than liquid water.
Water that is in the cracks of rocks can freeze and cause the cracks to become larger. Overtime, the rock erodes.

19. Water as an ideal solvent.
Many substances (solutes) can dissolve in water.
Water readily crosses the cell membrane, and therefore substances that are soluble in water can diffuse more easily.

20. Diffusion
The net movement of particles from an area of higher concentration to an area of lower concentration
Temperature and pressure can affect the rate (time) of diffusion.

21. Diffusion animation

22. Polymers: molecule made up of many repeating units
“repeating” monkeys
analogy
Repeating glucose  starch polymer
Ex: glucose monomer bonded to form starch polymer

23. SEM image of cellulose fibers
Carbohydrates
Carbon, hydrogen, and oxygen with a ratio of C1nH2nO1n
SEM image of cellulose fibers

24. Lipids
Fats, oils, waxes, and steroid rings

25. Proteins Carbon, hydrogen, oxygen, and nitrogen molecules
Hemoglobin in red blood cells

26. Nucleic acids
DNA, RNA, and ATP energy molecule