Chapter 2 Key Terms

Question 1

A given compound always contains exactly the same proportion of elements by mass

Answer 1

Law of definite proportions

Question 2

Mass is neither created nor destroyed

Answer 2

Law of conservation of mass

Question 3

When 2 elements form a series of compounds, the ratios of the masses of the second element that combine with 1 g of the first element can always be reduced to small whole numbers

Answer 3

Law of multiple proportions

Question 4

The weighted average mass of the atoms in a naturally occurring element

Answer 4

Atomic mass (atomic weight)

Question 5

At the same temperature and pressure, equal volumes of different gases contain the same number of particles

Answer 5

Avogadro’s hypothesis

Question 6

Tube in which “rays” (stream of electrons) emanate from the negative electrode (cathode)

Answer 6

Cathode-ray tube

Question 7

Negatively charged particle that moves around the nucleus of an atom

Answer 7

Electron

Question 8

The spontaneous decomposition of a nucleus to form a different nucleus

Answer 8

Radioactivity

Question 9

Atom with a dense center of positive charge with electrons moving around the nucleus at a distance that is large relative to the nuclear radius

Answer 9

Nuclear atom

Question 10

Small, dense center of positive charge in an atom

Answer 10

Nucleus

Question 11

Positively charged particle in an atomic nucleus

Answer 11

Proton

Question 12

Particle in the nucleus with the same mass as a proton with no charge

Answer 12

Neutron

Question 13

Atoms with the same number of protons but different numbers of neutrons

Answer 13

Isotopes

Question 14

Number of protons in the nucleus of an atom

Answer 14

Atomic number

Question 15

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

Answer 15

Mass number

Question 16

The force, or more accurately, the energy, that holds two atoms together in a compound

Answer 16

Chemical bond

Question 17

A type of bond in which electrons are shared by atoms

Answer 17

Covalent bond

Question 18

A bonded collection of 2 or more atoms of the same or different elements

Answer 18

Molecule

Question 19

The representation of a molecule in which the symbols for the elements are used to indicate the types of atoms present and subscripts are used to show the relative number of atoms

Answer 19

Chemical formula

Question 20

The representation of a molecule in which the relative positions of the atoms are shown and the bonds are indicated by lines

Answer 20

Structural formula

Question 21

A model of a molecule showing the relative sizes of the atoms and their relative orientations

Answer 21

Space-filling model

Question 22

A molecular model that distorts the sizes of atoms but shows bond relationships clearly

Answer 22

Ball-and-stick model

Question 23

An atom or a group of atoms that has a net positive or negative charge

Answer 23

Ion

Question 24

A positive ion; formed by loss of an electron

Answer 24

Cation

Question 25

A negative ion; formed by gain of an electron

Answer 25

Anion

Question 26

The electrostatic attraction between oppositely charged ions

Answer 26

Ionic bond

Question 27

A solid containing cations and anions that dissolves in water to give a solution containing the separated ions which are mobile and thus free to conduct electricity

Answer 27

Ionic solid (salt)

Question 28

An ion containing a number of atoms

Answer 28

Polyatomic ion

Question 29

A chart showing all the elements arranged in columns with similar chemical properties

Answer 29

Periodic table

Question 30

An element that gives up electrons relatively easily to form positive ions and is lustrous, malleable, ductile, and a good conductor of heat and electricity

Answer 30

Metal

Question 31

An element not exhibiting metallic characteristics; chemically, typically accepts electrons to form negative ions

Answer 31

Nonmetal

Question 32

A vertical column of elements having the same valence electron configuration and showing similar chemical properties

Answer 32

Group (family)

Question 33

Group 1A metals; very active elements that readily form ions with a 1+ charge when they react with nonmetals

Answer 33

Alkali metals

Question 34

Group 2A metals; all form ions with a 2+ charge with nonmetals

Answer 34

Alkaline earth metals

Question 35

Group 7A elements; all form diatomic molecules and react with metals to form salts containing ions with a 1- charge

Answer 35

Halogens

Question 36

Group 8A elements; all exist under normal conditions as monatomic (single-atom) gases and have little chemical reactivity

Answer 36

Noble gases

Question 37

Horizontal row of elements in the periodic table

Answer 37

Period

Question 38

Compounds composed of 2 elements

Answer 38

Binary compounds

Question 39

Compounds composed of 2 elements and contain a positive ion (cation) and a negative ion (anion)

Answer 39

Binary ionic compounds

Question 40

Compounds formed between 2 nonmetals

Answer 40

Binary covalent compounds

Question 41

Anions that contain an atom of a given element and different #s of oxygen atoms

Answer 41

Oxyanions

Question 42

A substance that produces hydrogen ions in solution; a proton donor

Answer 42

Acid