Question

An ion is an atom that has had what added or removed?

Answer 1

An ion is an atom that has had one or more electrons added or removed.

Cations are atoms that have lost one or more electrons. Anions are atoms that have gained one or more electrons. The number of electrons lost or gained determines the numeric part of the charge.

Example of cations:

$N{a}^{+}=$ sodium cation

$C{a}^{2+}=$ calcium cation

$A{l}^{3+}=$ aluminium cation

Example of anions:

$N^{3-}$ nitride anion

$F^{-}$ fluoride anion

$O^{2-}$ oxide anion