Chapter 2 - Atoms, Molecules, and Ions

Question 1

law of constant composition / law of definite proportions

Answer 1

a law stating that a given compound always contains elements in exactly the same proportion by mass

Question 2

law of multiple proportions

Answer 2

a law stating that when two elements form a series of compounds, the ratios of the masses of the second element that combine with one gram of the first element can always be reduced to small whole numbers

Question 3

actinide series / actinides

Answer 3

the fourteen elements following actinium, located in the second row of the block below the main body of the periodic table

Question 4

alkali metal

Answer 4

a metal in Group 1A of the periodic table

Question 5

alkaline earth metal

Answer 5

an element in Group 2A of the periodic table

Question 6

anion

Answer 6

a negatively charged ion

Question 7

atomic mass unit

Answer 7

one-twelfth the mass of a carbon-12 atom

Question 8

atomic number

Answer 8

the number of protons in the nucleus of an atom

Question 9

atomic weight

Answer 9

the average atomic mass for the naturally occurring element

Question 10

binary compound

Answer 10

a compound formed from two elements

Question 11

binary ionic compound

Answer 11

a compound formed when a metal and a nonmetal react to form a cation and an anion

Question 12

cation

Answer 12

a positively charged ion

Question 13

chemical formula

Answer 13

a symbolic representation of a substance in which atomic symbols indicate the elements present and subscripts indicate the relative numbers of atoms

Question 14

compound

Answer 14

a substance with constant composition that can be broken down into its elements by a chemical process

Question 15

covalent bond

Answer 15

a type of bond in which atoms share electrons

Question 16

electron

Answer 16

a negatively charged particle that occupies the space around the nucleus of an atom

Question 17

group / family

Answer 17

the elements in any one column of the periodic table

Question 18

halogen

Answer 18

an element in Group 7A of the periodic table

Question 19

hydrate

Answer 19

a compound that contains water molecules weakly bound in its crystals

Question 20

ion

Answer 20

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

Question 21

ionic bond

Answer 21

type of bond formed between a positive and a negative ion resulting from the transfer of electrons

Question 22

ionic compound

Answer 22

a compound consisting of cation[s] and anion[s], formed from at least one metal and one nonmetal

Question 23

covalent compound / molecular compound

Answer 23

a compound consisting only of nonmetals

Question 24

isotopes

Answer 24

atoms with the same atomic number but different mass numbers due to a difference in the number of neutrons

Question 25

lanthanide series / lanthanides

Answer 25

the fourteen elements following lanthanum, located in the first row of the block below the main body of the periodic table

Question 26

mass number

Answer 26

the total number of protons and neutrons in a nucleus

Question 27

metal

Answer 27

an element that gives up electrons relatively easily and is lustrous, malleable, and a good conductor of heat and electricity

Question 28

metalloid / semimetal

Answer 28

an element having both metallic and nonmetallic properties

Question 29

molecule

Answer 29

a neutral particle consisting of more than one atom in which the atoms are covalently bonded to each other

Question 30

neutron

Answer 30

a particle in the atomic nucleus with a mass approximately equal to that of the proton but with no charge

Question 31

noble gas

Answer 31

an element in Group 8A of the periodic table

Question 32

nonmetal

Answer 32

an element that does not exhibit the characteristics of a metal

Question 33

nuclear atom

Answer 33

the modern concept of the atom as having a dense center of positive charge [the nucleus] and electrons moving around the outside

Question 34

nucleus

Answer 34

the small, dense center of positive charge in an atom

Question 35

oxyanion / oxoanion

Answer 35

a polyatomic anion containing oxygen

Question 36

periodic table

Answer 36

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

Question 37

period / series

Answer 37

a horizontal row of elements in the periodic table

Question 38

polyatomic ion

Answer 38

an ion consisting of two or more atoms

Question 39

proton

Answer 39

a positively charged particle in an atomic nucleus

Question 40

main group elements / representative elements

Answer 40

elements in the “A” groups of the periodic table

Question 41

transition elements / transition metals

Answer 41

the elements in the central region of the periodic table—those in the “B” groups of periods 4-7