Chapter 2 Terms

Question 1

Matter

Answer 1

Anything that occupies space and has mass

Question 2

Element

Answer 2

A substance that cannot be broken down to other substances by chemical means

Question 3

Trace Elements

Answer 3

An element that is essential for life but required in extremely minute amounts

Question 4

Compound

Answer 4

A substance containing two or more elements in a fixed ratio. For example, table salt (NaCl) consists of one atom of the element sodium (Na) for every atom of chlorine (Cl)

Question 5

Atom

Answer 5

The smallest unit of matter that retains the properties of an element

Question 6

Proton

Answer 6

A subatomic particle with a single positive electrical charge, found in the nucleus of an atom

Question 7

Electron

Answer 7

A subatomic particle with a single negative electrical charge. One or more electrons move around the nucleus of an atom.

Question 8

Neutron

Answer 8

An electrically neutral particle (a particle having no electrical charge), found in the nucleus of an atom

Question 9

Nucleus

Answer 9

An atom’s central core, containing protons and neutrons

Question 10

Atomic Number

Answer 10

The number of protons in each atom of a particular element

Question 11

Mass Number

Answer 11

The sum of the number of protons and neutrons in an atom’s nucleus

Question 12

Atomic Mass

Answer 12

The approximate total mass of an atom; also called atomic weight. Given as a whole number, the atomic mass approximately equals the mass number

Question 13

Isotope

Answer 13

A variant form of an atom. Isotopes of an element have the same number of protons but different numbers of neutrons

Question 14

Radioactive Isotope

Answer 14

An isotope whose nucleus decays spontaneously, giving off particles and energy

Question 15

Electron Shell

Answer 15

An energy level representing the distance of an electron from the nucleus of an atom

Question 16

Chemical Bond

Answer 16

An attraction between two atoms resulting from a sharing of outer-shell electrons or the presence of opposite charges on the atoms. The bonded atoms gain complete outer electron shells

Question 17

Ion

Answer 17

An atom that has gained or lost one or more electrons, thus acquiring a charge

Question 18

Ionic Bond

Answer 18

A chemical bond resulting from the attraction between oppositely charged ions

Question 19

Covalent Bond

Answer 19

An attraction between atoms that share one or more pairs of outer-shell electrons; symbolized by a single line between the atoms

Question 20

Molecule

Answer 20

A group of two or more atoms held together by covalent bonds

Question 21

Double Bond

Answer 21

A type of covalent bond in which two atoms share two pairs of electrons; symbolized by a pair of lines between the bonded atoms

Question 22

Electronegativity

Answer 22

The attraction of a given atom for the electrons of a covalent bond

Question 23

Nonpolar Covalent Bond

Answer 23

A covalent bond in which electrons are shared equally between two atoms of similar electronegativity

Question 24

Polar Covalent Bond

Answer 24

A covalent bond between atoms that differ in electronegativity. The shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive

Question 25

Polar Molecule

Answer 25

A molecule containing polar covalent bonds

Question 26

Hydrogen Bond

Answer 26

A type of weak chemical bond formed when the partially positive hydrogen atom participating in a polar covalent bond in one molecule is attracted to the partially negative atom participating in a polar covalent bond in another molecule (or in another part of the same macromolecule)

Question 27

Cohesion

Answer 27

The binding together of like molecules, often by hydrogen bonds

Question 28

Adhesion

Answer 28

The attraction between different kinds of molecules

Question 29

Surface Tension

Answer 29

A measure of how difficult it is to stretch or break the surface of a liquid. Water has a high surface tension because of the hydrogen bonding of surface molecules

Question 30

Heat

Answer 30

Thermal energy; the amount of energy associated with the movement of the atoms and molecules in a body of matter. Heat is energy in its most random form

Question 31

Temperature

Answer 31

A measure of the intensity of heat in degrees, reflecting the average kinetic energy or speed of molecules

Question 32

Solution

Answer 32

A liquid consisting of a homogeneous mixture of two or more substances, consisting of a dissolving agent, called the solvent, and a substance that is dissolved, called the solute

Question 33

Solvent

Answer 33

The dissolving agent of a solution. Water is the most versatile solvent known

Question 34

Solute

Answer 34

A substance that is dissolved in a solution

Question 35

Aqueous Solution

Answer 35

A solution in which water is the solvent

Question 36

Acid

Answer 36

A substance that increases the hydrogen ion concentration in a solution

Question 37

Base

Answer 37

A substance that decreases the hydrogen ion (H) concentration in a solution

Question 38

pH Scale

Answer 38

A measure of the relative acidity of a solution, ranging in value from 0 (most acidic) to 14 (most basic). The letter pH stand for potential hydrogen and refer to the concentration of hydrogen ions (H).

Question 39

Buffer

Answer 39

A chemical substance that resists changes in pH by accepting hydrogen ions from or donating hydrogen ions to solutions

Question 40

Acid Precipitation

Answer 40

Rain, snow, or fog with a pH below 5.6

Question 41

Chemical Reaction

Answer 41

The making and breaking of chemical bonds, leading to changes in the composition of matter

Question 42

Reactant

Answer 42

A starting material in a chemical reaction

Question 43

Product

Answer 43

An ending material in a chemical reaction