The Chemistry of Life Unit 3 Chapter 6

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

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

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

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

How covalent bonds form Click on image to play video.

Ionic bond: transferred electrons between two atoms

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

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

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

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

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

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

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.

Cohesion and hydrogen bonds

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.

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.

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.

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.

Diffusion animation

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

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

Lipids Fats, oils, waxes, and steroid rings

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

Nucleic acids DNA, RNA, and ATP energy molecule