Ions and Cations Explained | Common Anions and Cations Table

Ions are electrically charged atoms or molecules formed by the loss or gain of electrons. They are fundamental to chemistry, electrochemistry, and many engineering processes including corrosion, electrolysis, and material reactions.

This page explains the difference between cations and anions and provides tables of commonly used monoatomic and polyatomic ions.

Introduction

Ions are divided into two groups; cations and anions. Cations have a positive charge and are formed when atoms lose electrons. Typical cations include sodium (Na+), calcium (Ca²⁺), and magnesium (Mg²⁺). Anions have a negative charge and are formed when atoms gain electrons. Typical anions include chloride (Cl-), sulfate (SO₄^2-), and bicarbonate (HCO₃-).

Common Monatomic Cations and Anions

The table below lists commonly encountered monoatomic ions used in chemistry and engineering calculations.

Cations				Anions
Symbol	Name	Symbol	Name	Symbol	Name
H+	hydrogen ion	Hg₂²⁺	mercury(I) mercurous	H-	hydride
Li+	lithium ion	Hg²⁺	mercury(II) mercuric	F-	fluoride
Na+	sodium ion	Fe²⁺	iron(II) ferrous	Cl-	chloride
K+	potassium ion	Fe³⁺	iron(III) ferric	Br-	bromide
Rb+	rubidium ion	Pb²⁺	lead(II) plumbous	I-	iodide
Cs+	cesium ion	Be²⁺	beryllium ion	O^2-	oxide
Pb⁴⁺	lead(IV) plumbic	Sn²⁺	tin(II) stannous	S^2-	sulfide
Mg²⁺	magnesium ion	Sn⁴⁺	tin(IV) stannic	Se^2-	selenide
Ca²⁺	calcium ion	Sr²⁺	strontium ion	Te^2-	telluride
Co²⁺	cobalt(II) cobaltous	Co³⁺	cobalt(III) cobaltic	*	*
Ba²⁺	barium ion	Cr²⁺	chromium(II) chromous	*	*
Ag+	silver ion	Cr³⁺	chromium(III) chromic	N^3-	nitride
Ra²⁺	radium ion	Al³⁺	aluminum ion	*	*
Ni²⁺	nickel ion	Au+	gold(I) aurous	P^3-	phosphide
Zn²⁺	zinc ion	Au³⁺	gold(III) auric	As^3-	arsenide
Cu+	copper(I) cuprous	Cu²⁺	copper(II) cupric	*	*

Common Polyatomic Anions

Polyatomic ions consist of multiple atoms bonded together carrying a net electrical charge.

Symbol	Name	Symbol	Name	Symbol	Name
NO₃-	nitrate	ClO₄-	perchlorate	SO₄^2-	sulfate
NO₂-	nitrite	ClO₃-	chlorate	HSO₄-	hydrogen sulfate
CrO₄^2-	chromate	ClO₂-	chlorite	SO₃^2-	sulfite
Cr₂O₇^2-	dichromate	ClO-	hypochlorite	HSO₃-	hydrogen sulfite
CN-	cyanide	IO₄-	periodate	C₂O₄^2-	oxalate
MnO₄-	permanganate	IO₃-	iodate	HC₂O₄-	hydrogen oxalate
OH-	hydroxide	IO-	hypoiodite	PO₄^3-	phosphate
O₂^2-	peroxide	BrO₃-	bromate	HPO₄^2-	hydrogen phosphate
NH₂-	amide	BrO-	hypobromite	PO₃^3-	phosphite
CO₃^2-	carbonate	HCO₃-	hydrogen carbonate	H₂PO₄-	dihydrogen phosphate

Summary of Ions, Cations and Anions

Cations are positively charged ions formed by loss of electrons.
Anions are negatively charged ions formed by gain of electrons.
Monoatomic ions consist of a single atom.
Polyatomic ions consist of multiple atoms bonded together.
Ions are essential in chemical reactions, electrochemistry, and materials engineering.

Ions and Cations

Introduction

Common Monatomic Cations and Anions

Common Polyatomic Anions

Summary of Ions, Cations and Anions

See Also