G-1

GLOSSARY

A

absolute zero

the zero point on the Kelvin

(absolute) temperature scale. See also Kelvin
temperature scale. [2.8, 12.6]

acid (1) A substance that produces

when

dissolved in water. (2) A proton donor.
(3) An electron pair acceptor. A substance that bonds
to an electron pair. [15.1]

acid anhydride A nonmetal oxide that reacts with water

to form an acid. [13.8]

acid ionization constant

The equilibrium constant

for the ionization of a weak acid in water. [16.11]

activation energy The amount of energy needed to start

a chemical reaction. [8.5, 16.8]

activity series of metals A listing of metallic elements

in descending order of reactivity. [17.5]

actual yield The amount of product actually produced in

a chemical reaction (compared with the theoretical
yield). [9.6]

addition reaction In organic chemistry, a reaction in

which two substances join together to produce one
substance. [19.9]

alcohol An organic compound consisting of an

group bonded to a carbon atom in a nonaromatic
hydrocarbon group; alcohols are classified as primary
(1°), secondary (2°), or tertiary (3°), depending on
whether the carbon atom to which the

group is

attached is bonded to one, two, or three other carbon
atoms, respectively. [19.14]

aldehyde An organic compound that contains the

group. The general formula is

. [19.17]

alkali metal An element (except H) from Group 1A

of the periodic table. [10.4]

alkaline earth metal An element from Group 2A

of the periodic table. [10.4]

alkane (saturated hydrocarbon) A compound

composed of carbon and hydrogen, having only single
bonds between the atoms; also known as paraffin
hydrocarbon. See also alkene and alkyne. [19.4]

alkene (unsaturated hydrocarbon) A hydrocarbon

whose molecules have at least one carbon–carbon
double bond. [19.7]

alkyl group An organic group derived from an alkane by

removal of one H atom. The general formula is
(e.g.,

methyl). Alkyl groups are generally

indicated by the letter

[19.6]

alkyne (unsaturated hydrocarbon) A hydrocarbon

whose molecules have at least one carbon–carbon triple
bond. [19.7]

R

.

CH

3

,

C

n

H

2n + 1

RCHO

¬

CHO

¬

OH

¬

OH

(K

a

)

(H

3

O

+

)

H

+

-

273°C,

allotrope A substance existing in two or more molecular

or crystalline forms (e. g., graphite and diamond are
two allotropic forms of carbon). [12.17]

alpha particle ( ) A particle emitted from a nucleus of

an atom during radioactive decay; it consists of two
protons and two neutrons with a mass of about 4 amu
and a charge of

it is considered to be a doubly

charged helium atom. [18.3]

amino acid An organic compound containing two

functional groups—an amino group

and a

carboxyl group

Amino acids are the building

blocks for proteins. [20.4]

amorphous A solid without shape or form. [1.7]
amphoteric (substance) A substance having properties

of both an acid and a base. [15.3]

anion A negatively charged ion. See also ion.

[3.8, 5.5, 6.2]

anode The electrode where oxidation occurs in an

electrochemical reaction. [17.6]

aqueous solution A water solution. [16.3]
aromatic compound An organic compound whose

molecules contain a benzene ring or that has properties
resembling benzene. [19.10]

artificial radioactivity Radioactivity produced in

nuclides during some types of transmutations.
Artificial radioactive nuclides behave like natural
radioactive elements in two ways: They disintegrate
in a definite fashion, and they have a specific half-life.
Sometimes called induced radioactivity. [18.6]

1 atmosphere The standard atmospheric pressure;

that is, the pressure exerted by a column of mercury
760 mm high at a temperature of
See also atmospheric pressure. [12.3]

atmospheric pressure The pressure experienced by

objects on Earth as a result of the layer of air
surrounding our planet. A pressure of 1 atmosphere
(1 atm) is the pressure that will support a column of
mercury 760 mm high at

[12.3]

atom The smallest particle of an element that can enter

into a chemical reaction. [3.1]

atomic mass The average relative mass of the isotopes

of an element referred to the atomic mass of carbon-12.
[5.9]

atomic mass number (A) The sum of the protons and

neutrons in the nucleus of an atom. [5.11]

atomic mass unit (amu) A unit of mass equal

to one-twelfth the mass of a carbon-12 atom. [5.11]

atomic number (Z) The number of protons in the

nucleus of an atom of a given element. See also
isotopic notation. [5.7]

0°C.

0°C.

(COOH)

.

(NH

2

)

+

2;

A

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G LO S S A RY

atomic theory The theory that substances are composed

of atoms, and that chemical reactions are explained by
the properties and the interactions of these atoms.
[5.2, Ch. 10]

Avogadro’s law Equal volumes of different gases at the

same temperature and pressure contain equal numbers
of molecules. [12.11]

Avogadro’s number

the number of

formula units in 1 mole. [7.1, 9.1]

B

balanced equation A chemical equation having the

same number of each kind of atom and the same
electrical charge on each side of the equation. [8.2]

barometer A device used to measure atmospheric

pressure. [12.3]

base A substance whose properties are due to the

liberation of hydroxide

ions into a water

solution. [15.1]

basic anhydride A metal oxide that reacts with water

to form a base. [13.8]

beta particle ( ) A particle identical in charge

and mass to an electron. [18.3]

binary compound A compound composed of two

different elements. [6.4]

biochemistry The branch of chemistry concerned with

chemical reactions occurring in living organisms. [20.1]

boiling point The temperature at which the vapor

pressure of a liquid is equal to the pressure above the
liquid. It is called the normal boiling when the pressure
is 1 atmosphere. [13.5]

bond length The distance between two nuclei that are

joined by a chemical bond. [13.10]

Boyle’s law The relationship between pressure and

volume of a gas. At constant temperature, the volume
of a fixed mass of gas is inversely proportional to the
pressure (

constant). [12.5]

Brownian movement The random motion of colloidal

particles. [15.14]

buffer solution A solution that resists changes in pH

when diluted or when small amounts of a strong acid or
strong base are added. [16.14]

C

calorie (cal) A commonly used unit of heat energy;

1 calorie is a quantity of heat energy that will raise
the temperature of 1 g of water

(e.g., from 14.5

to

). Also, 4.184 joules

calorie exactly.

See also joule. [4.6]

capillary action The spontaneous rising of a liquid in a

narrow tube, which results from the cohesive forces
within the liquid and the adhesive forces between the
liquid and the walls of the container. [13.4]

carbohydrate A polyhydroxy aldehyde or polyhydroxy

ketone, or a compound that upon hydrolysis yields a
polyhydroxy aldehyde or ketone; sugars, starch, and
cellulose are examples. [20.2]

=

1

15.5°C

1°C

PV =

1-12

(OH

-

)

6.022 * 10

23

;

carbonyl group The structure

.

[19.17]

carboxyl group The functional group of carboxylic acids:

[19.19]

carboxylic acid An organic compound having a carboxyl

group. [19.19]

catalyst A substance that influences the rate of a

reaction and can be recovered essentially unchanged at
the end of the reaction. [16.8]

cathode The electrode where reduction occurs in an

electrochemical reaction. [17.6]

cation A positively charged ion. See also ion. [3.8, 5.5]
Celsius temperature scale

The temperature scale

on which water freezes at

and boils at

at

1 atm pressure. [2.8]

chain reaction A self-sustaining nuclear or chemical

reaction in which the products cause the reaction to
continue or to increase in magnitude. [18.8]

Charles’ law At constant pressure, the volume of a fixed

mass of any gas is directly proportional to the absolute
temperature (

constant). [12.6]

chemical bond The attractive force that holds atoms

together in a compound. [Ch. 11]

chemical change A change producing products that differ

in composition from the original substances. [4.3]

chemical equation A shorthand expression showing the

reactants and the products of a chemical change
(for example,

). [4.3, 8.1]

chemical equilibrium The state in which the rate of the

forward reaction equals the rate of the reverse reaction
in a chemical change. [16.3]

chemical family See groups or families of elements.
chemical formula A shorthand method for showing the

composition of a compound, using symbols of the
elements. [3.9]

chemical kinetics The study of reaction rates and

reaction mechanisms. [16.2]

chemical properties The ability of a substance to form

new substances either by reaction with other
substances or by decomposition. [4.1]

chemistry The science of the composition, structure,

properties, and reactions of matter, especially of atomic
and molecular systems. [1.2]

chlorofluorocarbons (CFCs) A group of compounds

made of carbon, chlorine, and fluorine. [12.17]

colligative properties Properties of a solution that

depend on the number of solute particles in solution,
and not on the nature of the solute (examples:
vapor pressure lowering, freezing point depression,
boiling point elevation). [14.7]

colloid A dispersion in which the dispersed particles are

larger than the solute ions or molecules of a true
solution and smaller than the particles of a mechanical
suspension. [15.13]

2

H

2

O = 2

H

2

+

O

2

V

>T =

100°C

0°C

(°C)

¬

C

¬

OH

O

C

O

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G LO S S A RY

G-3

combination reaction A direct union or combination of

two substances to produce one new substance. [8.4]

combustion A chemical reaction in which heat and light

are given off; generally, the process of burning or
uniting a substance with oxygen. [19.4]

common-ion effect The shift of a chemical equilibrium

caused by the addition of an ion common to the ions
in the equilibrium. [16.12]

common names Arbitrary names that are not based

on the chemical composition of compounds
(examples: quick silver for mercury, laughing gas
for nitrous oxide). [6.1]

compound A distinct substance composed of two or

more elements combined in a definite proportion by
mass. [3.8]

concentrated solution A solution containing a relatively

large amount of dissolved solute. [14.6]

concentration of a solution A quantitative expression

of the amount of dissolved solute in a certain quantity
of solvent. [14.2]

condensation The process by which molecules in the

gaseous state return to the liquid state. [13.3]

conjugate acid–base Two molecules or ions whose

formulas differ by one

(The acid is the species with

the

and the base is the species without the

)

[15.1]

copolymer A polymer containing two different kinds of

monomer units. [19.21]

covalent bond A chemical bond formed between two

atoms by sharing a pair of electrons. [11.5]

critical mass The minimum quantity of mass required to

support a self-sustaining chain reaction. [18.8]

curie (Ci) A unit of radioactivity indicating the rate of

decay of a radioactive substance: 1 Ci
disintegrations per second. [18.7]

D

Dalton’s atomic model The first modern atomic theory

to state that elements are composed of minute
individual particles called atoms. [5.2]

Dalton’s law of partial pressures The total pressure of

a mixture of gases is the sum of the partial pressures
exerted by each of the gases in the mixture. [12.10]

decomposition reaction A breaking down, or

decomposition, of one substance into two or more
different substances. [8.4]

density The mass of an object divided by its volume. [2.19]
dialysis The process by which a parchment membrane

allows the passage of true solutions but prevents the
passage of colloidal dispersions. [15.16]

diatomic molecules The molecules of elements that always

contain two atoms. Seven elements occur as diatomic
molecules: and

[3.17]

diffusion The property by which gases and liquids mix

spontaneously because of the random motion of their
particles. [12.2]

I

2

.

H

2

,

N

2

,

O

2

,

F

2

,

Cl

2

,

Br

2

,

=

3.7 * 10

10

H

+

.

H

+

,

H

+

.

dilute solution A solution containing a relatively small

amount of dissolved solute. [14.6]

dipeptide Two -amino acids joined by a peptide

linkage. [20.4]

dipole A molecule that is electrically asymmetrical,

causing it to be oppositely charged at two points. [11.6]

disaccharide A carbohydrate that yields two

monosaccharide units when hydrolyzed. [20.2]

dissociation The process by which a salt separates into

individual ions when dissolved in water. [15.6]

DNA Deoxyribonucleic acid; a high-molar-mass polymer

of nucleotides, present in all living matter, that contains
the genetic code that transmits hereditary
characteristics. [20.6]

double bond A covalent bond in which two pairs of

electrons are shared. [11.5, 19.2]

double-displacement reaction A reaction of two

compounds to produce two different compounds by
exchanging the components of the reacting
compounds. [8.4]

ductile A property of metals; can be drawn in wires. [3.4]

E

effusion The process by which gas molecules pass

through a tiny orifice from a region of high pressure
to a region of lower pressure. [12.2]

Einstein’s mass–energy equation

the

relationship between mass and energy. [18.12]

electrolysis The process whereby electrical energy is

used to bring about a chemical change. [17.6]

electrolyte A substance whose aqueous solution

conducts electricity. [15.5]

electrolytic cell An electrolysis apparatus in which

electrical energy from an outside source is used to
produce a chemical change. [17.6]

electron A subatomic particle that exists outside the

nucleus and carries a negative electrical charge. [5.6]

electron configuration The orbital arrangement of

electrons in an atom. [10.5]

electron-dot structure See Lewis structure.
electronegativity The relative attraction that an atom has

for a pair of shared electrons in a covalent bond. [11.6]

electron shell See principal energy levels of electrons.
element A basic building block of matter that cannot be

broken down into simpler substances by ordinary
chemical changes; in 1994, there were 111 known
elements. [3.1]

empirical formula A chemical formula that gives the

smallest whole-number ratio of atoms in a
compound—that is, the relative number of atoms of
each element in the compound; also known as the
simplest formula. [7.4]

endothermic reaction A chemical reaction that absorbs

heat. [8.5]

energy The capacity of matter to do work. [4.5]

E = mc

2

:

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G LO S S A RY

energy levels of electrons Areas in which electrons are

located at various distances from the nucleus. [10.4]

energy sublevels The s, p, d, and f orbitals within a

principal energy level occupied by electrons in an atom.
[10.4]

enzyme A protein that catalyzes a biochemical reaction.

[20.5]

equilibrium A dynamic state in which two or more

opposing processes are taking place at the same time
and at the same rate. [16.3]

equilibrium constant

A constant representing

the concentrations of the reactants and the products in
a chemical reaction at equilibrium. [16.9]

essential amino acid An amino acid that is not

synthesized by the body and therefore must be
supplied in the diet. [20.4]

ester An organic compound derived from a carboxylic

acid and an alcohol. The general formula is

[19.20]

ether An organic compound having two hydrocarbon

groups attached to an oxygen atom. The general
formula is

. [19.16]

evaporation The escape of molecules from the liquid

state to the gas or vapor state. [13.2]

exothermic reaction A chemical reaction in which heat

is released as a product. [8.5]

F

Fahrenheit temperature scale

The temperature

scale on which water freezes at

and boils at

at 1 atm pressure. [2.8]

fats and oils Esters of fatty acids and glycerol. See also

triacylglycerol. [20.3]

fatty acids Long-chain carboxylic acids present in lipids

(fats and oils). [20.3]

formula equation A chemical equation in which all the

reactants and products are written in their molecular,
or normal, formula expression; also called a molecular
equation. [15.12]

formula unit The atom or molecule indicated by the

formula of a substance under consideration
(examples:

). [7.1]

free radical A neutral atom or group of atoms having

one or more unpaired electrons. [12.17]

freezing or melting point The temperature at which

the solid and liquid states of a substance are in
equilibrium. [13.6]

frequency A measurement of the number of waves that

pass a particular point per second. [10.2]

functional group An atom or group of atoms that

characterizes a class of organic compounds. For
example,

is the functional group of carboxylic

acids. [19.2]

¬

COOH

Mg,

O

2

,

H

2

O

212°F

32°F

(°F)

R

¬

O

¬

R

œ

R

¬

C

¬

OR

œ

O

(K

eq

)

G

galvanic cell See voltaic cell.
gamma ray ( ) High-energy photons emitted by

radioactive nuclei; they have no electrical charge and
no measurable mass. [18.3]

gas A state of matter that has no shape or definite

volume so that the substance completely fills its
container. [1.7]

Gay-Lussac’s law At constant volume, the pressure of a

fixed mass of gas is directly proportional to the
absolute temperature (

constant). [12.7]

Gay-Lussac’s law of combining volumes (of gases)

When measured at the same temperature and pressure,
the ratios of the volumes of reacting gases are small
whole numbers. [12.11]

genes Basic units of heredity that consist primarily of DNA

and proteins and occur in the chromosomes. [20.7]

Graham’s law of effusion The rates of effusion of two

gases at the same temperature and pressure are
inversely proportional to the square roots of their
densities or molar masses. [12.2]

greenhouse effect The effect of CO

2

and other

greenhouse gases to warm the atmosphere by
absorbing energy near the surface of the earth, which
can lead to global warming. [8.6]

ground state The lowest available enrgy level within

an atom. [10.3]

groups or families (of elements) Vertical groups of

elements in the periodic table (1A, 2A, and so on).
Families of elements that have similar outer-orbital
electron structures. [10.6]

H

half-life The time required for one-half of a specific

amount of a radioactive nuclide to disintegrate; half-
lives of the elements range from a fraction of a second
to billions of years. [18.2]

halogenation The substitution of a halogen atom for a

hydrogen atom in an organic compound. [19.3]

halogens Group 7A of the periodic table; consists of the

elements fluorine, chlorine, bromine, iodine, and
astatine. [10.4]

heat A form of energy associated with the motion of

small particles of matter. [2.8]

heat of fusion The energy required to change 1 gram of

a solid into a liquid at its melting point. [13.7]

heat of reaction The quantity of heat produced by a

chemical reaction. [8.5]

heat of vaporization The amount of heat required to

change 1 gram of a liquid to a vapor at its normal
boiling point. [13.7]

heterogeneous Matter without a uniform composition—

having two or more components or phases. [1.8]

homogeneous Matter that has uniform properties

throughout. [1.8]

P

>T =

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G LO S S A RY

G-5

homologous series A series of compounds in which the

members differ from one another by a regular
increment. For example, each successive member of
the alkane series of hydrocarbons differs by a
group. [19.4]

hydrate A solid that contains water molecules as a part

of its crystalline structure. [13.9]

hydrocarbon A compound composed entirely of carbon

and hydrogen. [8.5]

hydrogen bond The intermolecular force acting between

molecules that contain hydrogen covalently bonded to
the highly electronegative elements F, O, and N. [13.8]

hydrolysis Chemical reaction with water in which the

water molecule is split into

and

[16.13]

hydronium ion The result of a proton combining with a

polar water molecule to form a hydrated hydrogen ion,

[15.1]

hypothesis A tentative explanation of certain facts to

provide a basis for further experimentation. [1.5]

I

ideal gas A gas that behaves precisely according to the

Kinetic Molecular Theory; also called a perfect gas.
[12.2]

ideal gas law

that is, the volume of a gas

varies directly with the number of gas molecules and the
absolute temperature and inversely with the pressure.
[12.14]

immiscible Incapable of mixing; immiscible liquids do

not form a solution with one another. [14.2]

induced radioactivity See artificial radioactivity.
ion A positively or negatively charged atom or group of

atoms. See also cation, anion. [3.8, 5.5]

ionic bond The chemical bond between a positively

charged ion and a negatively charged ion. [11.3]

ionic compound A compound that is composed of ions

(e.g.,

) [3.8, 6.3]

ionization The formation of ions, which occurs as the

result of a chemical reaction of certain substances with
water. [15.6]

ionization energy The energy required to remove an

electron from an atom, an ion, or a molecule. [11.1]

ionizing radiation Radiation with enough energy to

dislocate bonding electrons and create ions when
passing through matter. [18.4]

ion product constant for water

An equilibrium

constant defined as the product of the

ion

concentration and the

ion concentration, each in

moles per liter.

at

.

[16.10]

isomerism The phenomenon of two or more compounds

having the same molecular formula but different
molecular structures. [19.5]

isomers Compounds having identical molecular formulas

but different structural formulas. [19.5]

25°C

K

w

=

[H

+

][OH

-

] = 1 * 10

-

14

OH

-

H

+

(K

w

)

Na

+

Cl

-

PV = nRT;

H

3

O

+

.

OH

-

.

H

+

CH

2

isotope An atom of an element that has the same atomic

number but a different atomic mass. Since their atomic
numbers are identical, isotopes vary only in the number
of neutrons in the nucleus. [5.10]

isotopic notation Notation for an isotope of an element

where the subscript is the atomic number, the
superscript is the mass number, and they are attached
on the left of the symbol for the element. (For
example, hydrogen-1 is notated as

.) See also atomic

number, mass number. [5.10]

IUPAC International Union of Pure and Applied

Chemistry, which devised (in 1921) and continually
upgrades the system of nomenclature for inorganic and
organic compounds. [6.1]

J

joule (J) The SI unit of energy. See also calorie. [4.6]

K

Kelvin temperature scale (K) Absolute temperature

scale starting at absolute zero, the lowest temperature
possible. Freezing and boiling points of water on this
scale are 273 K and 373 K, respectively, at 1 atm
pressure. See also absolute zero. [2.8, 12.6]

ketone An organic compound that contains a carbonyl

group between two other carbon atoms. The general
formula is

[19.17]

kilocalorie (kcal) 1000 cal; the kilocalorie is also known

as the nutritional or large Calorie, used for measuring
the energy produced by food. [4.6]

kilogram (kg) The standard unit of mass in the metric

system; 1 kilogram equals 2.205 pounds. [2.9]

kilojoule (kJ) 1000 J. [4.6]
kinetic energy (KE) The energy that matter possesses

due to its motion;

[4.5]

kinetic-molecular theory (KMT) A group of

assumptions used to explain the behavior and
properties of gases. [12.2]

L

law A statement of the occurrence of natural phenomena

that occur with unvarying uniformity under the same
conditions. [1.5]

law of conservation of energy Energy can be neither

created nor destroyed, but it can be transformed from
one form to another. [4.8]

law of conservation of mass No change is observed in

the total mass of the substances involved in a chemical
reaction; that is, the mass of the products equals the
mass of the reactants. [4.4]

law of definite composition A compound always

contains two or more elements in a definite proportion
by mass. [5.3]

law of multiple proportions Atoms of two or more

elements may combine in different ratios to produce
more than one compound. [5.3]

KE = 1

>2

mv

2

.

R

2

C = O

.

1
1

H

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G LO S S A RY

Le Châtelier’s principle If a stress is applied to a

system in equilibrium, the system will respond in such
a way as to relieve that stress and restore equilibrium
under a new set of conditions. [16.4]

Lewis structure A method of indicating the covalent

bonds between atoms in a molecule or an ion such that
a pair of electrons

represents the valence electrons

forming the covalent bond. [11.2]

limiting reactant A reactant that limits the amount of

product formed because it is present in insufficient
amount compared with the other reactants. [9.6]

linear structure In the VSEPR model, an arrangement

where the pairs of electrons are arranged 180° apart for
maximum separation. [11.11]

line spectrum Colored lines generated when light

emitted by a gas is passed through a spectroscope. Each
element possesses a unique set of line spectra. [10.3]

lipids Organic compounds found in living organisms that

are water insoluble, but soluble in such fat solvents as
diethyl ether, benzene, and carbon tetrachloride;
examples are fats, oils, and steroids. [20.3]

liquid A state of matter in which the particles move

about freely while the substance retains a definite
volume; thus, liquids flow and take the shape of their
containers. [1.7]

liter (L) A unit of volume commonly used in chemistry;

the volume of a kilogram of water at

4°C. [2.10]

logarithm (log) The power to which 10 must be raised

to give a certain number. The log of 100 is 2.0. [15.9]

M

macromolecule See polymer.
malleable A property of metals; can be rolled or

hammered into sheets. [3.4]

mass The quantity or amount of matter that an object

possesses. [2.7]

mass defect The difference between the actual mass of

an atom of an isotope and the calculated mass of the
protons and neutrons in the nucleus of that atom.
[18.12]

mass number (A) The sum of the protons and neutrons

in the nucleus of a given isotope of an atom.
See also isotopic notation. [5.10]

mass percent solution The grams of solute in 100 g of a

solution. [14.6]

matter Anything that has mass and occupies space. [1.6]
meiosis The process of cell division to form a sperm cell

and an egg cell in which each cell formed contains half
of the chromosomes found in the normal single cell.
[20.7]

melting or freezing point See freezing or melting point.
meniscus The shape of the surface of a liquid when placed

in a glass cylinder. It can be concave or convex. [13.4]

1

L = 1000

mL;

(

≠

)

metal An element that is solid at room temperature and

whose properties include luster, ductility, malleability,
and good conductivity of heat and electricity; metals
tend to lose their valence electrons and become
positive ions. [3.4]

metalloid An element having properties that are

intermediate between those of metals and nonmetals
(for example, silicon); these elements are useful in
electronics. [3.4]

meter (m) The standard unit of length in the SI and

metric systems; 1 meter equals 39.37 inches. [2.5]

metric system A decimal system of measurements.

See also SI. [2.5]

miscible Capable of mixing and forming a solution. [14.2]
mitosis Ordinary cell division in which a DNA molecule

is duplicated by uncoiling to single strands and then
reassembling with complementary nucleotides. Each
new cell contains the normal number of chromosomes.
[20.7]

mixture Matter containing two or more substances,

which can be present in variable amounts; mixtures can
be homogeneous (sugar water) or heterogeneous
(sand and water). [1.8]

molality (m) An expression of the number of moles of

solute dissolved in 1000 g of solvent. [14.7]

molarity (M) The number of moles of solute per liter of

solution. [14.6]

molar mass The mass of Avogadro’s number of atoms or

molecules. The sum of the atomic masses of all the
atoms in an element, compound, or ion. The mass of a
mole of any formula unit. It is also known as the
molecular weight. [7.1, 9.1]

molar solution A solution containing 1 mole of solute

per liter of solution. [14.6]

molar volume (of a gas) The volume of 1 mol of a gas

at STP equals 22.4 L/mol. [12.12]

mole The amount of a substance containing the same

number of formula units

as there are in

exactly 12 g of

One mole is equal to the molar

mass in grams of any substance. [7.1]

molecular formula The total number of atoms of each

element present in one molecule of a compound; also
known as the true formula. See also empirical formula.
[7.4]

molecule The smallest uncharged individual unit of a

compound formed by the union of two or more atoms.
[3.8]

mole ratio A ratio between the number of moles of any

two species involved in a chemical reaction; the mole
ratio is used as a conversion factor in stoichiometric
calculations. [9.2]

monomer The small unit or units that undergo

polymerization to form a polymer. [19.21]

monosaccharide A carbohydrate that cannot be

hydrolyzed to simpler carbohydrate units (for example,
simple sugars like glucose or fructose). [20.2]

12

C.

16.022 * 10

23

2

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G LO S S A RY

G-7

N

net ionic equation A chemical equation that includes

only those molecules and ions that have changed in the
chemical reaction. [15.12]

neutralization The reaction of an acid and a base to

form a salt plus water. [15.10]

neutron A subatomic particle that is electrically neutral

and is found in the nucleus of an atom. [5.6]

noble gases A family of elements in the periodic table—

helium, neon, argon, krypton, xenon, and radon—that
contain a particularly stable electron structure. [10.4]

nonelectrolyte A substance whose aqueous solutions do

not conduct electricity. [15.5]

nonmetal An element that has properties the opposite of

metals: lack of luster, relatively low melting point and
density, and generally poor conduction of heat and
electricity. Nonmetals may or may not be solid at room
temperature (examples: carbon, bromine, nitrogen);
many are gases. They are located mainly in the upper
right-hand corner of the periodic table. [3.8]

nonpolar covalent bond A covalent bond between two

atoms with the same electronegativity value; thus, the
electrons are shared equally between the two atoms.
[11.6]

normal boiling point The temperature at which the

vapor pressure of a liquid equals 1 atm or 760 torr
pressure. [13.5]

nuclear binding energy The energy equivalent to the

mass defect; that is, the amount of energy required to
break a nucleus into its individual protons and
neutrons. [18.12]

nuclear fission The splitting of a heavy nuclide into two

or more intermediate-sized fragments when struck in a
particular way by a neutron. As the atom is split, it
releases energy and two or three more neutrons that
can then cause another nuclear fission. [18.8]

nuclear fusion The uniting of two light elements to form

one heavier nucleus, which is accompanied by the
release of energy. [18.11]

nucleic acids Complex organic acids essential to life and

found in the nucleus of living cells. They consist of
thousands of units called nucleotides. Include DNA
and RNA. [20.6]

nucleon A collective term for the neutrons and protons

in the nucleus of an atom. [18.1]

nucleotide The building-block unit for nucleic acids. A

phosphate group, a sugar residue, and a nitrogenous
organic base are bonded together to form a nucleotide.
[20.6]

nucleus The central part of an atom that contains all its

protons and neutrons. The nucleus is very dense and
has a positive electrical charge. [5.8]

nuclide A general term for any isotope of any atom.

[18.1]

O

oils See fats and oils.
one atmosphere The standard atmospheric pressure;

that is, the pressure exerted by a column of mercury
760 mm high at a temperature of 0°C. [12.3]

orbital A cloudlike region around the nucleus where

electrons are located. Orbitals are considered to be
energy sublevels (s, p, d, f) within the principal energy
levels. See also principal energy levels. [10.3, 10.4]

orbital diagram A way of showing the arrangement of

electrons in an atom, where boxes with small arrows
indicating the electrons represent orbitals. [10.5]

organic chemistry The branch of chemistry that deals

with carbon compounds but does not imply that these
compounds must originate from some form of life.
See also vital-force theory. [19.1]

osmosis The diffusion of water, either pure or from a

dilute solution, through a semipermeable membrane
into a solution of higher concentration. [14.8]

oxidation An increase in the oxidation number of an

atom as a result of losing electrons. [17.2]

oxidation number A small number representing the

state of oxidation of an atom. For an ion, it is the
positive or negative charge on the ion; for covalently
bonded atoms, it is a positive or negative number
assigned to the more electronegative atom; in free
elements, it is zero. [17.1]

oxidation–reduction A chemical reaction wherein

electrons are transferred from one element to another;
also known as redox. [17.2]

oxidation state See oxidation number. [17.1]
oxidizing agent A substance that causes an increase in the

oxidation state of another substance. The oxidizing agent
is reduced during the course of the reaction. [17.2]

ozone layer A high concentration of ozone located in

the stratosphere that shields the earth from damaging
ultraviolet radiation. [12.15]

P

partial pressure The pressure exerted independently by

each gas in a mixture of gases. [12.10]

parts per million (ppm) A measurement of the

concentration of dilute solutions now commonly used
by chemists in place of mass percent. [14.6]

Pauli exclusion principle An atomic orbital can hold a

maximum of two electrons, which must have opposite
spins. [10.4]

peptide linkage The amide bond in a protein molecule;

bonds one amino acid to another. [20.4]

percent composition of a compound The mass percent

represented by each element in a compound. [7.3]

percent yield The ratio of the actual yield to the

theoretical yield multiplied by 100. [9.6]

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G-8

G LO S S A RY

perfect gas A gas that behaves precisely according to

theory; also called an ideal gas. [12.2]

periodic table An arrangement of the elements

according to their atomic numbers. The table consists
of horizontal rows, or periods, and vertical columns, or
families, of elements. Each period ends with a noble
gas. [3.5, 10.6]

period of elements The horizontal groupings (rows) of

elements in the periodic table. [3.5, 10.6]

pH A method of expressing the

concentration (acidity)

of a solution;

is a neutral

solution,

is acidic, and

is basic. [15.9]

phase A homogeneous part of a system separated from

other parts by a physical boundary. [1.8]

photon Theoretically, a tiny packet of energy that

streams with others of its kind to produce a beam of
light. [10.2]

physical change A change in form (such as size, shape, or

physical state) without a change in composition. [4.2]

physical properties Inherent physical characteristics of

a substance that can be determined without altering its
composition: color, taste, odor, state of matter, density,
melting point, boiling point. [4.1]

physical states of matter Solids, liquids, and gases. [1.7]
physiological saline solution A solution of 0.90%

sodium chloride that is isotonic (has the same osmotic
pressure) with blood plasma. [14.8]

pOH A method of expressing the basicity of a solution.

is a neutral solution,

is basic, and

is acidic. [16.11]

polar covalent bond A covalent bond between two

atoms with differing electronegativity values, resulting
in unequal sharing of bonding electrons. [11.5]

polyatomic ion An ion composed of more than one

atom. [6.5]

polyhydroxyl alcohol An alcohol that has more than

one group.

[19.14]

polymer (macromolecule) A natural or synthetic giant

molecule formed from smaller molecules (monomers).
[19.21]

polymerization The process of forming large, high-

molar-mass molecules from smaller units. [19.21]

polypeptide A peptide chain containing up to 50 amino

acid units. [20.4]

polysaccharide A carbohydrate that can be hydrolyzed

to many monosaccharide units; cellulose, starch, and
glycogen are examples. [20.2]

positron A particle with a

charge having the mass of

an electron (a positive electron). [18.1]

potential energy (PE) Stored energy, or the energy of

an object due to its relative position. [4.5]

pressure Force per unit area; expressed in many units,

such as mm Hg, atm,

torr, and pascal. [12.3]

lb

>in.

2

,

+

1

¬

OH

pOH 7 7

pOH 6 7

pOH = - log[OH

-

].

pOH = 7

pH 7 7

pH 6 7

pH = - log[H

+

],

pH = 7

H

+

primary alcohol An alcohol in which the carbon atom

bonded to the

group is bonded to only one other

carbon atom. [19.14]

principal energy levels of electrons Existing within

the atom, these energy levels contain orbitals
within which electrons are found. See also orbital,
electron. [10.4]

product A chemical substance produced from reactants

by a chemical change. [4.3]

properties The characteristics, or traits, of substances

that give them their unique identities. Properties are
classified as physical or chemical. [4.1]

protein A polymer consisting mainly of -amino acids

linked together; occurs in all animal and vegetable
matter. [20.4]

proton A subatomic particle found in the nucleus of the

atom that carries a positive electrical charge and a mass
of about 1 amu. An

ion is a proton. [5.6]

Q

quanta Small discrete increments of energy. From the

theory proposed by physicist Max Planck that energy is
emitted in energy quanta rather than a continuous
stream. [10.3]

quantum mechanics or wave mechanics The modern

theory of atomic structure based on the wave
properties of matter. [10.3]

R

rad (radiation absorbed dose) A unit of absorbed

radiation indicating the energy absorbed from any
ionizing radiation; 1 rad

J of energy absorbed

per kilogram of matter. [18.7]

radioactive decay The process by which a radioactive

element emits particles or rays and is transformed into
another element. [18.2]

radioactive disintegration series The spontaneous

decay of a certain radioactive nuclide by emission of
alpha and beta particles from the nucleus, finally
stopping at a stable isotope of lead or bismuth. [18.4]

radioactivity The spontaneous emission of radiation

from the nucleus of an atom. [18.1]

rate of reaction The rate at which the reactants of a

chemical reaction disappear and the products form.
[16.2]

reactant A chemical substance entering into a reaction.

[4.3]

redox See oxidation–reduction. [17.2]
reducing agent A substance that causes a decrease in

the oxidation state of another substance; the reducing
agent is oxidized during the course of a reaction. [17.2]

reduction A decrease in the oxidation number of an

element as a result of gaining electrons. [17.2]

=

0.01

H

+

¬

OH

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G LO S S A RY

G-9

rem (roentgen equivalent to man) A unit of radiation-

dose equivalent taking into account that the energy
absorbed from different sources does not produce the
same degree of biological effect. [18.7]

representative element An element in one of the A

groups in the periodic table. [10.6]

resonance structure A molecule or ion that has multiple

Lewis structures. See also Lewis structure. [11.8]

reversible chemical reaction A chemical reaction in

which the products formed react to produce the
original reactants. A double arrow is used to indicate
that a reaction is reversible. [16.1]

RNA Ribonucleic acid; a high-molar-mass polymer of

nucleotides present in all living matter. Its main
function is to direct the synthesis of proteins. [20.6]

roentgen (R) A unit of exposure of gamma radiation based

on the quantity of ionization produced in air. [18.7]

rounding off numbers The process by which the value

of the last digit retained is determined after dropping
nonsignificant digits. [2.3]

S

salts Ionic compounds of cations and anions. [Ch. 6, 15.4]
saponification The hydrolysis of a fat or an oil with an

aqueous strong base (NaOH) to yield a soap. [20.3]

saturated hydrocarbon A hydrocarbon that has only

single bonds between carbon atoms; classified as
alkanes. [19.3]

saturated solution A solution containing dissolved

solute in equilibrium with undissolved solute. [14.3]

scientific laws Simple statements of natural phenomena

to which no exceptions are known under the given
conditions. [1.5]

scientific method A method of solving problems by

observation; recording and evaluating data of an
experiment; formulating hypotheses and theories to
explain the behavior of nature; and devising additional
experiments to test the hypotheses and theories to see
if they are correct. [1.5]

scientific notation A convenient way of expressing large

and small numbers using powers of 10. To write a
number as a power of 10 move the decimal point in the
original number so that it is located after the first
nonzero digit, and follow the new number by a
multiplication sign and 10 with an exponent (called its
power) that is the number of places the decimal point
was moved. Example:

[2.4]

secondary alcohol An alcohol in which the carbon atom

bonded to the

group is bonded to two other

carbon atoms. [19.14]

semipermeable membrane A membrane that allows the

passage of water (solvent) molecules through it in
either direction but prevents the passage of larger
solute molecules or ions. [14.8]

¬

OH

2468 = 2.468 * 10

3

.

SI An agreed-upon standard system of measurements

used by scientists around the world (Système
Internationale). See also metric system. [2.5]

significant figures The number of digits that are known

plus one estimated digit are considered significant in a
measured quantity; also called significant digits.
[2.3, Appendix I]

simplest formula See empirical formula.
single bond A covalent bond in which one pair of

electrons is shared between two atoms. [11.5]

single-displacement reaction A reaction of an element

and a compound that yields a different element and a
different compound. [8.4]

soap A salt of a long-carbon-chain fatty acid. [20.3]
solid A state of matter having a definite shape and a

definite volume, whose particles cohere rigidly to one
another, so that a solid can be independent of its
container. [1.7]

solubility An amount of solute that will dissolve in a

specific amount of solvent under stated conditions.
[14.2]

solubility product constant

The equilibrium

constant for the solubility of a slightly soluble salt.
[16.12]

solute The substance that is dissolved—or the least

abundant component—in a solution. [14.1]

solution A system in which one or more substances are

homogeneously mixed or dissolved in another
substance. [14.1]

solvent The dissolving agent or the most abundant

component in a solution. [14.1]

specific gravity The ratio of the density of one

substance to the density of another substance taken as
a standard. Water is usually the standard for liquids and
solids; air, for gases. [2.9]

specific heat The quantity of heat required to

change the temperature of 1 g of any substance
by 1°C. [4.6]

spectator ion An ion in solution that does not undergo

chemical change during a chemical reaction. [15.10]

speed (of a wave) A measurement of how fast a wave

travels through space. [10.2]

spin A property of an electron that describes its

appearance of spinning on an axis like a globe; the
electron can spin in only two directions, and, to occupy
the same orbital, two electrons must spin in opposite
directions. See also orbital. [10.4]

standard boiling point See normal boiling point.
standard conditions See STP.
standard temperature and pressure See STP.
Stock (nomenclature) System A system that uses

Roman numerals to name elements that form more
than one type of cation. (For example:

iron(II);

iron(III).) [6.4]

Fe

3+

,

Fe

2+

,

(K

sp

)

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G-10

G LO S S A RY

stoichiometry The area of chemistry that deals with the

quantitative relationships among reactants and
products in a chemical reaction. [9.2]

STP (standard temperature and pressure) 0°C

(273 K) and 1 atm (760 torr); also known as standard
conditions. [12.8]

strong electrolyte An electrolyte that is essentially 100%

ionized in aqueous solution. [15.7]

subatomic particles Particles found within the atom,

mainly protons, neutrons, and electrons. [5.6]

sublimation The process of going directly from the solid

state to the vapor state without becoming a liquid. [13.2]

subscript Number that appears partially below the line

and to the right of a symbol of an element (example:

). [3.9]

substance Matter that is homogeneous and has a

definite, fixed composition; substances occur in two
forms—as elements and as compounds. [1.8]

substrate In biochemical reactions, the substrate is the

unit acted upon by an enzyme. [20.5]

supersaturated solution A solution containing more

solute than needed for a saturated solution at a
particular temperature. Supersaturated solutions tend
to be unstable; jarring the container or dropping in a
“seed” crystal will cause crystallization of the excess
solute. [14.3]

surface tension The resistance of a liquid to an increase

in its surface area. [13.4]

symbol In chemistry, an abbreviation for the name of an

element. [3.4]

system A body of matter under consideration. [1.8]

T

temperature A measure of the intensity of heat,

or of how hot or cold a system is; the SI unit is the
kelvin (K). [2.8]

tertiary alcohol An alcohol in which the carbon atom

bonded to the

group is bonded to three other

carbon atoms. [19.14]

tetrahedral structure An arrangement of the VSEPR

model where four pairs of electrons are placed 109.5°
degrees apart to form a tetrahedron. [11.11, 19.2]

theoretical yield The maximum amount of product that

can be produced according to a balanced equation. [9.6]

theory An explanation of the general principles of certain

phenomena with considerable evidence to support it; a
well-established hypothesis. [1.5]

Thomson model of the atom Thomson asserted that

atoms are not indivisible but are composed of smaller
parts; they contain both positively and negatively
charged particles—protons as well as electrons. [5.6]

titration The process of measuring the volume of one

reagent required to react with a measured mass or
volume of another reagent. [15.10]

torr A unit of pressure (1 torr

1 mm Hg). [12.3]

=

¬

OH

H

2

SO

4

total ionic equation An equation that shows

compounds in the form in which they actually exist.
Strong electrolytes are written as ions in solution,
whereas nonelectrolytes, weak electrolytes,
precipitates, and gases are written in the
un-ionized form. [15.12]

transcription The process of forming RNA from DNA.

[20.6]

transition elements The metallic elements characterized

by increasing numbers of d and f electrons. These
elements are located in Groups 1B–8B of the periodic
table. [10.6]

transmutation The conversion of one element into

another element. [18.5]

transuranium element An element that has an atomic

number higher than that of uranium

[18.13]

triacylglycerol (triglyceride) An ester of glycerol and

three molecules of fatty acids. [20.3]

trigonal planar An arrangement of atoms in the VSEPR

model where the three pairs of electrons are placed
120° apart on a flat plane. [11.11]

triple bond A covalent bond in which three pairs of

electrons are shared between two atoms. [11.5, 19.2]

Tyndall effect An intense beam of light is clearly

visible when passed through a colloidal dispersion,
but is not visible when passed through a true solution.
[15.14]

U

unsaturated hydrocarbon A hydrocarbon whose

molecules contain one or more double or triple bonds
between two carbon atoms; classified as alkenes,
alkynes, and aromatic compounds. [19.3]

unsaturated solution A solution containing less solute

per unit volume than its corresponding saturated
solution. [14.6]

V

valence electron An electron in the outermost energy

level of an atom; these electrons are the ones
involved in bonding atoms together to form
compounds. [10.5]

valence shell electron pair repulsion (VSEPR)

theory A theory for predicting the shape of covalent
compounds based on the repulsion of bonded and
nonbondend pairs of valence electrons. [11.11]

vapor pressure The pressure exerted by a vapor in

equilibrium with its liquid. [13.3]

vaporization See evaporation. [13.2]
vapor pressure curve A graph generated by plotting the

temperature of a liquid on the x-axis and its vapor
pressure on the y-axis. Any point on the curve
represents an equilibrium between the vapor and
liquid. [13.5]

17922.

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G LO S S A RY

G-11

vital-force theory A theory that held that organic

substances could originate only from some form of
living material. The theory was overthrown early in the
19th century. [19.1]

volatile (substance) A substance that evaporates

readily; a liquid with a high vapor pressure and a low
boiling point. [13.3]

voltaic cell A cell that produces electric current from a

spontaneous chemical reaction. [17.6]

volume The amount of space occupied by matter;

measured in SI units by cubic meters

but also

commonly in liters and milliliters. [2.7]

volume percent (solution) The volume of solute in

100 mL of solution. [14.6]

(m

3

)

W

water of crystallization Water molecules that are part

of a crystalline structure, as in a hydrate; also called
water of hydration. [13.9]

water of hydration See water of crystallization.
wavelength The distance between consecutive peaks and

troughs in a wave; symbolized by the Greek letter
lambda. [10.2]

weak electrolyte A substance that is ionized to a small

extent in aqueous solution. [15.7]

weight A measure of Earth’s gravitational attraction for a

body (object). [2.7]

word equation A statement in words, in equation form,

of the substances involved in a chemical reaction. [8.2]

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