Ions:

Cations: + charged particles (metals) always smaller than its neutral atom (↓ e-repulsions and most dist e- are removed)

Anions: - charged particles (nonmetals) always larger than its neutral atom (↑ e- repulson)

Ionic radius: same (general) trend as atomic radius, until met/nonmetal boundary @ staircase

· ¯ as move left to rt across period (increased Z_eff)

· as move down column of table (increased n)

Isoelectronic:  Ions that possess the same number of e-

O ^2-

F ^-

Na ⁺

Mg ²⁺

Al ³⁺