Key terms, Chapter 2

Question 1

acid

Answer 1

compound that releases hydrogen ions (H+) in solution

Question 2

activation energy

Answer 2

amount of energy greater than the energy contained in the reactants, which must be overcome for a reaction to proceed

Question 3

adenosine triphosphate (ATP)

Answer 3

nucleotide containing ribose and an adenine base that is essential in energy transfer

Question 4

amino acid

Answer 4

building block of proteins; characterized by an amino and carboxyl functional groups and a variable side-chain

Question 5

anion

Answer 5

atom with a negative charge

Question 6

atom

Answer 6

smallest unit of an element that retains the unique properties of that element

Question 7

atomic number

Answer 7

number of protons in the nucleus of an atom

Question 8

base

Answer 8

compound that accepts hydrogen ions (H+) in solution

Question 9

bond

Answer 9

electrical force linking atoms

Question 10

buffer

Answer 10

solution containing a weak acid or a weak base that opposes wide fluctuations in the pH of body fluids

Question 11

carbohydrate

Answer 11

class of organic compounds built from sugars, molecules containing carbon, hydrogen, and oxygen in a 1-2-1 ratio

Question 12

catalyst

Answer 12

substance that increases the rate of a chemical reaction without itself being changed in the process

Question 13

cation

Answer 13

atom with a positive charge

Question 14

chemical energy

Answer 14

form of energy that is absorbed as chemical bonds form, stored as they are maintained, and released as they are broken

Question 15

colloid

Answer 15

liquid mixture in which the solute particles consist of clumps of molecules large enough to scatter light

Question 16

compound

Answer 16

substance composed of two or more different elements joined by chemical bonds

Question 17

concentration

Answer 17

number of particles within a given space

Question 18

covalent bond

Answer 18

chemical bond in which two atoms share electrons, thereby completing their valence shells

Question 19

decomposition reaction

Answer 19

type of catabolic reaction in which one or more bonds within a larger molecule are broken, resulting in the release of smaller molecules or atoms

Question 20

denaturation

Answer 20

change in the structure of a molecule through physical or chemical means

Question 21

deoxyribonucleic acid (DNA)

Answer 21

deoxyribose-containing nucleotide that stores genetic information

Question 22

disaccharide

Answer 22

pair of carbohydrate monomers bonded by dehydration synthesis via a glycosidic bond

Question 23

disulfide bond

Answer 23

covalent bond formed within a polypeptide between sulfide groups of sulfur-containing amino acids, for example, cysteine

Question 24

electron

Answer 24

subatomic particle having a negative charge and nearly no mass; found orbiting the atom’s nucleus

Question 25

electron shell

Answer 25

area of space a given distance from an atom’s nucleus in which electrons are grouped

Question 26

element

Answer 26

substance that cannot be created or broken down by ordinary chemical means

Question 27

enzyme

Answer 27

protein or RNA that catalyzes chemical reactions

Question 28

exchange reaction

Answer 28

type of chemical reaction in which bonds are both formed and broken, resulting in the transfer of components

Question 29

functional group

Answer 29

group of atoms linked by strong covalent bonds that tends to behave as a distinct unit in chemical reactions with other atoms

Question 30

hydrogen bond

Answer 30

dipole-dipole bond in which a hydrogen atom covalently bonded to an electronegative atom is weakly attracted to a second electronegative atom

Question 31

inorganic compound

Answer 31

substance that does not contain both carbon and hydrogen

Question 32

ion

Answer 32

atom with an overall positive or negative charge

Question 33

ionic bond

Answer 33

attraction between an anion and a cation

Question 34

isotope

Answer 34

one of the variations of an element in which the number of neutrons differ from each other

Question 35

kinetic energy

Answer 35

energy that matter possesses because of its motion

Question 36

lipid

Answer 36

class of non-polar organic compounds built from hydrocarbons and distinguished by the fact that they are not soluble in water

Question 37

macromolecule

Answer 37

large molecule formed by covalent bonding

Question 38

mass number

Answer 38

sum of the number of protons and neutrons in the nucleus of an atom

Question 39

matter

Answer 39

physical substance; that which occupies space and has mass