Chapter 3

Question 1

enantiomers

Answer 1

one of two compounds that are mirror images of each other and that differ in shape due to the presence of an asymmetric carbon.

Question 2

mass number

Answer 2

the total number of protons and neutrons in an atoms nucleus.

Question 3

atom

Answer 3

the smallest unit of matter that retains the properties of an element.

Question 4

heat

Answer 4

thermal energy in transfer from one body of matter to another.

Question 5

van der walls interactions

Answer 5

weak interactions between molecules or parts of molecules that result from transient (lasting only for a short time) local partial charges.

Question 6

solution

Answer 6

a liquid that is a homogenous mixture of two or more substances.

Question 7

chemical reactions

Answer 7

the making and breaking of chemical bonds, leading to changes in the composition of matter.

Question 8

evaporative cooling

Answer 8

the process in which the surface of an object becomes cooler during evaporation, a result of the molecules with the greatest kinetic energy changing from the liquid to the gaseous form.

Question 9

polar covalent bond

Answer 9

a covalent bond between atoms that differ in electronegativity. the shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive.

Question 10

chemical bonds

Answer 10

an attraction between two atoms, resulting from a sharing of outer-shell electrons or the presence of opposite charges on the atoms. the bonded atoms gain complete outer electron shells.

Question 11

isotopes

Answer 11

one of several atomic forms of an element, each with the same number of protons but a different number of neutrons, thus differing in atomic mass.

Question 12

covalent bond

Answer 12

a type of strong chemical bond in which two atoms share one or more pairs of valance electrons.

Question 13

kilocalorie

Answer 13

a thousand calories; the amount of heat energy required to raise the temperature of 1 kg of water by 1 degree celsius.

Question 14

ionic compounds

Answer 14

a compound resulting from the formation of an ionic bond; also called a salt.

Question 15

compound

Answer 15

a substance consisting of two or more different elements combined in a fixed ratio.

Question 16

ocean acidification

Answer 16

the process by which the ocean’s pH is lowered (made more acidic) when excess carbon dioxide dissolves in seawater and forms carbonic bonds.

Question 17

molecule

Answer 17

two or more atoms held together by covalent bonds.

Question 18

hydroxide ion

Answer 18

a water molecule that has lost a proton; written as OH subscript minus.

Question 19

double bond

Answer 19

a double covalent bond; the sharing of two pairs of valance electrons by two atoms.

Question 20

valance shell

Answer 20

the outermost energy shell of an atom, containing the valance electrons involved in the chemical reactions of that atom.

Question 21

anion

Answer 21

a negatively charged atom

Question 22

valance

Answer 22

the bonding capacity of a given atom; the number of covalent bonds an atom can form, which usually equals the number of unpaired electrons in its outermost (valance) shell.

Question 23

hydrogen ion

Answer 23

a single proton with a charge of 1-plus. the dissociation of a water molecule leads to the generation of a hydroxide ion (O charge of 1-minus) and a hydrogen ion (charge of 1-plus); in water, the hydrogen ion is not found alone but associates with a water molecule to form a hydronium ion.