Electron Orbitals

Front

Atomic number

Back

The number of protons in the nucleus of an atom. In a neutral atom, it is also equal to the number of electrons.

Front

Atomic radius

Back

The distance from the nucleus to the outermost electrons of an atom. Measured in picometers (pm).

Front

Aufbau principle

Back

A rule that electrons will occupy the lowest energy subshell that is available.

Front

Chemical family

Back

A vertical column in the periodic table where elements have the same number of valence electrons and similar chemical properties.

Front

Diagonal rule

Back

A rule that shows the order in which subshells are filled with electrons. Heavier elements may not follow it exactly.

Front

Electron configuration

Back

A description of the shells, subshells, and orbitals occupied by electrons.

Front

Hund’s rule

Back

A rule stating that electrons will occupy all unoccupied orbitals within a subshell before sharing orbitals.

Front

Orbital

Back

A region in space occupied by an electron or pair of electrons, described by a mathematical function.

Front

Pauli exclusion principle

Back

A rule stating that no two electrons can have exactly the same location and state. If two electrons share the same shell, subshell, and orbital, they must have different spins.

Front

Period

Back

A horizontal row of the periodic table.