Download CP Chem and Water Review Guide

CP BIOLOGY
Chapter 2 Review Topics
Chemistry and Radioisotopes
Name ____________
These are topics and vocabulary terms covered in Chapter 2 which may appear on the
chapter test or quizzes. Also see pp. 30-39, 55-56 in text for more review.
Elements, Atoms, and Molecules
 Why is chemistry important to biology?
o Living matter, metabolism – chemical processes
o Chemical signals, reactions in environment cycle materials
 Atomic Theory – structure of atom
 Matter – has mass and volume, Law of Conservation
 Elements (one kind of atom) and compounds (more than one kind, in ratio)
 Major elements in bio – C, H, O, N
 Some minor elements – ex. Cl, Na, P, S – used in reactions or cell function
 Trace elements – needed in small amounts, ex. Iron – oxygen in blood
Atomic Structure
 Nucleus – particles, charges, most mass of atom
 Electrons – cloud, charge, most volume of atom
 Energy levels, valence electrons determine chemical properties
 Octet Rule – 2-8-8 to fill valence
 Atomic number (protons only), mass number (protons + neutrons)
 Isotopes and average atomic mass – same element, different # neutrons
Radioisotopes
 Unstable – decay to a different element but now stable
 Half-life – time for ½ of sample to decay
 Uses: date fossils
o medical tests (PET scans) and cancer therapy
o research “tracers” show how atoms are used in biologic processes
o nuclear energy
Compounds and chemical bonding
 ions: electrons gained or lost  (+) or (-) charge
 ionic bonding – forms between (+) or (-) charged particles
o forms a crystal; dissociates in water individual ions
 Covalent bonding - shared valence electron pairs, forms molecules
o Bonds do not break in water but molecules separate
 Chemical formula – kinds and number of each atom
 Chemical Reactions – reactants and products; same atoms, different
combinations
CP BIOLOGY
Chapter 2 Review Topics
Water Properties and pH
Name ____________
These are topics and vocabulary terms covered in Chapter 2 which may appear on the
chapter test or quizzes. Also see pp. 40-44, 55-56 in text for more review.
The Water Molecule
 Why is water necessary for life?
 Polar covalent bonds – electrons not shared evenly around molecule
 Water molecule – more electrons on oxygen end (-)
 Shape is bent, has (+) and (-) poles
 Hydrogen bonds – H on one molecule  oxygen on another
Properties of water
What are they? Why are they important in living things?
 Cohesion – hydrogen bonds make water molecules stick together
o Surface tension – acts like a membrane for cells
o High heat capacity – absorbs or loses heat without changing temp
o Temperature moderation – keeps temp stable in organisms,
 constant ocean temp, slow season changes
o Cool on evaporating – water molecules on surface take heat away
o Why ice floats –less dense than liquid water, molecules farther apart
 Ice insulates ponds, so water below stays liquid
o Capillary action – water climbs up narrow tube, small spaces
 Adhesion – water forms hydrogen bonds to other substances
o Universal solvent – dissolves polar and ionic, but not nonpolar
o Dissolve in water – ions dissociate; molecules stay intact
o Capillary action – uses both cohesion and adhesion
 Blood vessels in animals, veins in plants
Solutions and Mixtures
 Solvent and solute – solvent= main part of a mixture
 Aqueous solution – solvent is water; fluids in all living things
 Suspension – too big to dissolve; ex. Blood - cells in watery fluid
Acids and bases
 pH : [H+] ion concentration
 acid – higher H+, pH below 7; base higher OH- (lower H+), pH above 7
 neutralization reaction: acid + base  salt (ionic) + water
 buffers – weak acid or base, minimizes pH change
 in humans: mostly pH 7; stomach –acid, pancreas – base, intestine - neutral