Chapter 3 Science Vocab

Front 1

atom

Back 1

the basic unit of a chemical element.

Front 2

electron

Back 2

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

Front 3

nucleus

Back 3

the central and most important part of an object, movement, or group, forming the basis for its activity and growth.

Front 4

proton

Back 4

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.

Front 5

energy level (orbit, shell)

Back 5

the fixed amount of energy that a system described by quantum mechanics, such as a molecule, atom, electron, or nucleus, can have.

Front 6

neutron

Back 6

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.

Front 7

atomic number

Back 7

the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table.

Front 8

isotope

Back 8

each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element.

Front 9

mass number

Back 9

the total number of protons and neutrons in a nucleus.

Front 10

atomic mass

Back 10

the mass of an atom of a chemical element expressed in atomic mass units. It is approximately equivalent to the number of protons and neutrons in the atom (the mass number) or to the average number allowing for the relative abundances of different isotopes.

Front 11

period

Back 11

the name given to a horizontal row of the periodic table. The periodic table has seven periods

Front 12

group

Back 12

a column of elements in the periodic table of the chemical elements.

Front 13

metal

Back 13

an effective conductor of electricity and heat can be defined as a metal.

Front 14

nonmetal

Back 14

is a chemical element that mostly lacks metallic attributes.

Front 15

metaloid

Back 15

an element (e.g., germanium or silicon) whose properties are intermediate between those of metals and solid nonmetals. They are electrical semiconductors.

Front 16

alkali metal

Back 16

any of the elements lithium, sodium, potassium, rubidium, cesium, and francium, occupying Group IA (1) of the periodic table. They are very reactive, electropositive, monovalent metals forming strongly alkaline hydroxides.

Front 17

alkaline earth metal

Back 17

They are reactive, electropositive, divalent metals, and form basic oxides that react with water to form comparatively insoluble hydroxides.

Front 18

transtition metal

Back 18

any of the set of metallic elements occupying a central block (Groups IVB–VIII, IB, and IIB, or 4–12) in the periodic table,

Front 19

halogen

Back 19

They are reactive nonmetallic elements that form strongly acidic compounds with hydrogen, from which simple salts can be made.

Front 20

noble gas

Back 20

They were long believed to be totally unreactive but compounds of xenon, krypton, and radon are now known.

Front 21

semiconductor

Back 21

a solid substance that has a conductivity between that of an insulator and that of most metals, either due to the addition of an impurity or because of temperature effects.

Front 22

APE MAN

Back 22

Atomic number

protons

electrons

Mass number

Atomic mass

neutrons