Cation
A positively charged ion produced when an atom or molecule loses one or more electrons.
Formula / equation
M → Mⁿ⁺ + n e⁻
Unit
C (charge)
In depth
Cations are smaller than their parent atoms because losing electrons reduces electron–electron repulsion and increases the effective nuclear pull on those remaining. Metals form cations readily, since they have low ionisation energies. In electrolysis cations migrate to the negatively charged cathode, which is the origin of the name.
Examples in the real world
Na⁺, Mg²⁺, Al³⁺, Fe³⁺, and the polyatomic ammonium ion NH₄⁺.