A monoatomic ion is an ion consisting of one or more atoms of a single element (unlike a polyatomic ion, which consists of more than one element in one ion). A type I binary ionic compound contains a metal (cation) that forms only one type of ion. A type II ionic compound contains a metal that forms more than one type of ion, i.e., ions with different charges.

Common type I cations
Hydrogen
Lithium	Li+
Sodium	Na+
Potassium	K+
Cesium	Cs+
Beryllium	Be2+
Magnesium	Mg2+
Calcium	Ca2+
Barium	Ba2+
Aluminum	Al3+
Silver	Ag+
Zinc	Zn2+

Common type II cations
iron(II)	Fe2+	ferrous
copper(II)	Cu2+	cupric
copper(I)	Cu+	cuprous

Common anions
hydride	H−
fluoride	F−
chloride	Cl−
bromide	Br−
iodide	I−
oxide	O2−
sulfide	S2−
nitride	N3−
phosphide	P3−

[edit] See also

• monatomic
• polyatomic ion