Chemistry Vocabulary - Unit 2

Question 1

Atomic Mass Unit (amu)

Answer 1

a unit of mass used to express atomic and molecular weights

Question 2

Isotope

Answer 2

each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei

Question 3

Atomic Number

Answer 3

the number of protons in the nucleus of an atom

Question 4

Mass Number

Answer 4

the total number of protons and neutrons in a nucleus

Question 5

Atomic Mass

Answer 5

the mass of an atom of a chemical element expressed in atomic mass units

Question 6

Valence Electron

Answer 6

a single electron or one of two or more electrons in the outer shell of an atom that is responsible for the chemical properties of the atom

Question 7

Half Life

Answer 7

the time taken for the radioactivity of a specified isotope to fall to half its original value

Question 8

Electron

Answer 8

a stable subatomic particle with a charge of negative electricity, found in all atoms and acting as the primary carrier of electricity in solids

Question 9

Proton

Answer 9

a stable subatomic particle occurring in all atomic nuclei, with a positive electric charge equal in magnitude to that of an electron, but of opposite sign

Question 10

Neutron

Answer 10

a subatomic particle of about the same mass as a proton but without an electric charge, present in all atomic nuclei except those of ordinary hydrogen

Question 11

Nucleus

Answer 11

the membrane-enclosed organelle within a cell that contains the chromosomes

Question 12

Orbital

Answer 12

each of the actual or potential patterns of electron density that may be formed in an atom or molecule by one or more electrons

Question 13

Ion

Answer 13

an atom or molecule with a net electric charge due to the loss or gain of one or more electrons

Question 14

Atomic Radius

Answer 14

The radius of an atom

Question 15

Electronegativity

Answer 15

a chemical property that describes the tendency of an atom or a functional group to attract electrons toward itself

Question 16

Group

Answer 16

a column in the periodic table of the chemical elements

Question 17

Period

Answer 17

The horizontal rows of the periodic table

Question 18

Periodic Law

Answer 18

a law stating that the elements, when listed in order of their atomic numbers (originally, atomic weights), fall into recurring groups

Question 19

Ionization Energy

Answer 19

the amount of energy required to remove an electron from an isolated atom or molecule

Question 20

New atom

Answer 20

when the number of protons in the atom changes