Chemistry Vocab

Question 0

The weighted average of the masses of the isotopes of an element

Answer 0

Atomic mass

Question 1

The smallest particle of an element that retains its identity in a chemical reaction

Answer 1

Atom

Question 2

The number of protons in the nucleus of an atom of an element

Answer 2

Atomic number

Question 3

Water that contains dissolved substances

Answer 3

Aqueous solution

Question 4

A substance that contains two or more elements chemically combines in a fixed proportion

Answer 4

Compound

Question 5

The ability of a substance to undergo a specify chemical change

Answer 5

Chemical property

Question 6

A substance that increases the rate of reaction by lowering the activation-energy barrier; the _______ is not used up in the reaction

Answer 6

Catalyst

Question 7

An expression that indicates the number and type of atoms present in the smallest representative unit of a substance.

Answer 7

Chemical formula

Question 8

An expression representing a chemical reaction; formulas of the reactants are connected by an arrow with the formulas for the products

Answer 8

Chemical equation

Question 9

A bond process by which hydrocarbons are broken down or rearranged into smaller, more useful molecules

Answer 9

Covalent bond

Question 10

The ratio of the mass of an object to its volume

Answer 10

Density

Question 11

A notation the depicts valence electrons as dots around the atomic symbol of the element; the symbol represents the inner electrons and atomic nucleus; also called Lewis dot structure

Answer 11

Electron dot structure

Question 12

The simplest form of matter that has a unique set of properties; an element cannot be broken down into simpler substance by chemical means

Answer 12

Element

Question 13

The lowest whole-number ratio of ions in an ionic compound; in magnesium chloride, the ratio of magnesium ions to chloride ions is 1:2 and the _____ ___ is MgCl2

Answer 13

Formula unit

Question 14

A vertical column of elements in the periodic table; the constituent elements of a group have similar chemical and physical properties

Answer 14

Group (periodic table)

Question 15

A molecule consisting of two atoms

Answer 15

Diatomic molecule

Question 16

A mixture that is not uniform in composition, components are not evenly distributed throughout the mixture

Answer 16

Heterogeneous mixture

Question 17

A mixture that is uniform in composition; components evenly distributed and not easily distinguished

Answer 17

Homogenous mixture

Question 18

A nonmetal in Group 7A of the periodic table

Answer 18

Halogen

Question 19

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

Answer 19

Ion

Question 20

Atoms of the same element that have the same atomic number but different atomic masses due to a different number of neutrons

Answer 20

Isotopes

Question 21

A compound composed of positive and negative ions

Answer 21

Ionic compound

Question 22

Anything that has mass and occupies space

Answer 22

Matter

Question 23

A neutral group of atoms joined together by covalent bonds

Answer 23

Molecule

Question 24

The tiny, dense central portion of an atom, composed of protons and neutrons

Answer 24

Nucleus

Question 25

An element in group 8A of the periodic table; the s and p sublevels of the highest occupied energy level are filled

Answer 25

Noble gas

Question 26

Atoms react by gaining or losing electrons so as to acquire stable electron structure of w noble gas, usually 8 valence electrons

Answer 26

Octet rule