Cation Definition and Examples

The hydronium cation is the simplest type of oxonium ion.
The hydronium cation is the simplest type of oxonium ion. Jacek FH, Wikipedia Commons

A cation is an ionic species with a positive charge. The word "cation" comes from the Greek word "kato," which means "down." A cation has more protons than electrons, giving it a net positive charge.

Cations with multiple charges may be given special names. For example, a cation with a +2 charge is a dication. One with a +3 charge is a trication. A zwitterion has both positive and negative charges at different regions of the molecule, yet an overall neutral charge.

The symbol for a cation is the element symbol or molecular formula, followed by a superscript of the charge. The number of the charge is given first, followed by a plus symbol. If the charge is one, the numeral is omitted.

Examples of Cations

Cations may be either ions of atoms or of molecules. Examples include:

  • Ag+
  • Al3+
  • Ba2+
  • Ca2+
  • H+
  • H3O+
  • Li+
  • Mg2+
  • NH4+
Format
mla apa chicago
Your Citation
Helmenstine, Anne Marie, Ph.D. "Cation Definition and Examples." ThoughtCo, Jan. 7, 2018, thoughtco.com/cation-definition-and-examples-602142. Helmenstine, Anne Marie, Ph.D. (2018, January 7). Cation Definition and Examples. Retrieved from https://www.thoughtco.com/cation-definition-and-examples-602142 Helmenstine, Anne Marie, Ph.D. "Cation Definition and Examples." ThoughtCo. https://www.thoughtco.com/cation-definition-and-examples-602142 (accessed May 26, 2018).