Ch. 2

Question 1

number of protons in the atomic nucleus; determines the element

Answer 1

atomic number

Question 2

negatively charged subatomic particle

Answer 2

electron

Question 3

a pure substance that consists only of atoms with the same number of protons

Answer 3

elements

Question 4

forms of an element that differ in the number of neutrons their atoms carry

Answer 4

isotopes

Question 5

the total number of protons and neutrons in the atomic nucleus

Answer 5

mass number

Question 6

uncharged subatomic particle that occurs in the atomic nucleus

Answer 6

neutron

Question 7

central core of an atom

Answer 7

nucleus

Question 8

positively charged subatomic particle that occurs in the nucleus of all atoms

Answer 8

proton

Question 9

process in which an atom emits energy and/or subatomic particles when its nucleus spontaneously breaks up

Answer 9

radioactive decay

Question 10

isotope with an unstable nucleus

Answer 10

radioisotope

Question 11

a substance with a detectable component

Answer 11

tracer

Question 12

atom with an unpaired electron

Answer 12

free radical

Question 13

atom or molecule that carries a net charge

Answer 13

ion

Question 14

model of electron distribution in an atom

Answer 14

shell model

Question 15

property of a substance that arises from the tendency of its molecules to resist separating from one another

Answer 15

cohesion

Question 16

amount of solute per unit volume of solution

Answer 16

concentration

Question 17

transition of a liquid to a vapor

Answer 17

evaporation

Question 18

attraction between a covalently bonded hydrogen atom and another atom taking part in a separate polar covalent bond

Answer 18

hydrogen bond

Question 19

a substance that dissolves easily in water

Answer 19

hydrophilic

Question 20

a substance that resists dissolving in water

Answer 20

hydrophobic

Question 21

compound that releases ions other than H+ and OH- when it dissolves in water

Answer 21

salt

Question 22

a dissolved substance

Answer 22

solute

Question 23

uniform mixture of solute completely dissolved in solvent

Answer 23

solution

Question 24

liquid in which other substances dissolve

Answer 24

solvent

Question 25

measure of molecular motion

Answer 25

temperature

Question 26

substance that releases hydrogen ions in water

Answer 26

acid

Question 27

substance that accepts hydrogen ions in water

Answer 27

base

Question 28

set of chemicals that can keep the pH of a solution stable by alternately donating and accepting ions that contribute to pH

Answer 28

buffer

Question 29

measure of the number of hydrogen ions in a water-based fluid

Answer 29

pH