Chapter 2

Front 1

electron

Back 1

a subatomic particle that has a negative charge and essentially zero mass

Front 2

radioactivity

Back 2

the spontaneous emission of high-energy radiation and particles by materials

Front 3

beta particle

Back 3

a radioactive emission that is a high-energy electron

Front 4

alpha particle

Back 4

a radioactive emission with a charge of 2+ and a mass equivalent to that of a helium nucleus

Front 5

nucleus

Back 5

the positively charge center of an atom that contains nearly all the atom's mass

Front 6

proton

Back 6

a positively charged subatomic particle present in the nucleus of an atom

Front 7

neutron

Back 7

an electrically neutral subatomic particle found in the nucleus of an atom

Front 8

atomic mass unit (amu)

Back 8

unit used to express the relative masses of atom and subatomic particles. it is exactly 1/12 the mass of one atom of carbon with six protons and six neutrons in its nucleus

Front 9

dalton (Da)

Back 9

a unit of mass identical to one atomic mass unit

Front 10

ion

Back 10

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

Front 11

isotopes

Back 11

atoms of an element containing different numbers of neutrons

Front 12

nuclide

Back 12

the nucleus of a specific isotope of an element

Front 13

atomic number (Z)

Back 13

the number of protons in the nucleus of an atom

Front 14

nucleon

Back 14

either a proton or a neutron in a nucleus

Front 15

mass number (A)

Back 15

the number or nucleons in an atom (protons + neutrons)

Front 16

periodic table of elements

Back 16

a chart of the elements in order of their atomic numbers and in a pattern based on their physical and chemical properties

Front 17

average atomic mass

Back 17

a weighted average of masses of all isotopes of an element, calculated by multiplying the natural abundance of each isotope by its mass in atomic mass units and then summing these products

Front 18

natural abundance

Back 18

the proportion of a particular isotope, usually expressed as a percentage relative to all the isotopes of that element in a natural sample

Front 19

halogens

Back 19

the elements in group 17 of the periodic table

Front 20

akali metals

Back 20

the elements in group 1 of the periodic table

Front 21

alkaline earth metals

Back 21

the elements in group 2 of the periodic table

Front 22

metals

Back 22

the elements on the left side of the periodic table that are typically shiny solids that conduct heat and energy well and are malleable and ductile

Front 23

nonmetals

Back 23

elements with properties opposite of metals - including poor conductivity of heat and electricity

Front 24

metalliods

Back 24

also called semimetals - elements along the border between metals and nonmetals in the periodic table, they have some metallic and nonmetallic properties

Front 25

main group elements - representative elements

Back 25

the elements in groups 1, 2, and 13 through 18 of the periodic table

Front 26

transition metals

Back 26

the elements in groups 3 through 12 of the periodic table

Front 27

noble gases

Back 27

the elements in group 18 of the periodic table

Front 28

law of multiple proportions

Back 28

the ratio of the two masses of one element that react with a given mass of another element to form two different compounds is the ratio of two small whole numbers

Front 29

molecular compound

Back 29

a compound composed of atoms held together in molecules by covalent bonds

Front 30

covalent bond

Back 30

a bond between two atoms created by sharing one or more pairs of electrons

Front 31

molecular formula

Back 31

a notation showing the number and type of atoms present in one molecule of a molecular compound

Front 32

ionic compound

Back 32

a compound composed of positively and negatively charged ions held together by electrostatic attraction

Front 33

cation

Back 33

a positively charged particle created when an atom or molecule loses one or more electrons

Front 34

anion

Back 34

a negatively charge particle created when an atom or molecule gains one or more electrons

Front 35

empirical formula

Back 35

a formula showing the smallest whole-number ratio of elements in a compound

Front 36

formula unit

Back 36

the smallest electrically neutral unit of an ionic compound

Front 37

polyatomic ions

Back 37

charged groups of two or more atoms joined together by covalent bonds

Front 38

oxoanions

Back 38

polyatomic ions that contain oxygen in combination with one or more other elements

Front 39

quarks

Back 39

elementary particles that combine to form neutrons and protons

Front 40

nucleosynthesis

Back 40

the natural formation of nuclei as a result of fusion and other nuclear processes