Unit Two – Atomic Structure, Periodic Table, & Nuclear Chemistry

Number of protons in the nucleus of an atom

Number of protons and neutrons

Smallest particle of an element

A one or two letter representation of an element

A subatomic particle that has a negative charge; smallest of subatomic particles

A class of elements characterized by physical properties that include shininess, malleability, ductility, and conductivity.

has one valence electron; highly reactive; found in the first column of the periodic table

A nuclear reaction in which a massive nucleus splits into smaller nuclei with the simultaneous release of energy.

A cluster of 2 protons and 2 neutrons emitted from a nucleus in one type of radioactivity

a region around the nucleus of an atom where electrons are likely to be found

A pure substance made of only one kind of atom

A particular region where electrons can “orbit” a nucleus.

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

A horizontal row of elements in the periodic table

Element that is usually a gas or brittle solid at room temperature; poor conductor of heat and electricity; tends to form anion

an element with 2 valence electrons, harder, higher melting point, and denser than alkali metals. Reactive, but less than corresponding alkali metal

combining of small nuclei into larger ones, releasing energy

an electron emitted from the nucleus during some kinds of radioactive decay

Atoms of the same element that have different numbers of neutrons

like charges repel, opposite charges attract

A method for representing an atom’s valence electrons using dots around the element symbol.

The largest subatomic particle; no charge; found in the nucleus of an atom

Group of element in the same column of the periodic table; they are similar chemical properties

Elements along the staircase. Have properties of both metals and nonmetals. Ex: Silicon

Contains nonmetals, 7 valence electrons in it’s outermost energy level. Very reactive

Energy (electromagnetic) waves given off during radioactive decay, fission, or fusion

The time required for one half of the atoms of a radioisotope to emit radiation or decay products

A region that is located at the center of an atom and contains most of the atom’s mass (protons and neutrons)

A subatomic particle that has a positive charge and that is found in the nucleus of an atom

the law that states that the repeating chemical and physical properties of elements change periodically with the atomic numbers of the elements

Electrons in the outermost energy level of an atom

A column on the periodic table

Family or group of elements with the complete outer electron levels; nonreactive or inert gases

the process in which a radioactive isotope tends to break down into a stable isotope of the same element or another element

energy during radioactive decay, fission, or fusion

States that atoms lose, gain or share electrons in order to acquire a full set of eight valence electrons