cation

IPA/ˈkætaɪən/
KK[kˈætˌaɪən]IPA/ˈkætaɪən/

cation — noun

  • cationsingular
  • cationsplural

1. an atom or small group of atoms whose electric charge is positive, causing it to

1.nounB2
Definition

an atom or small group of atoms whose electric charge is positive, causing it to be drawn toward the negative end when an electric current runs through a liquid

Example

Priya watched the copper cations move toward the cathode during her chemistry experiment.

cation + cathode collocation in electrolysis context

A sodium cation forms when a sodium atom gives away one of its electrons.

cation formation through electron loss

Common collocations
  • cation exchange
  • cation binding
  • cation channel
  • divalent cation
  • monovalent cation
Synonyms
  • positive ion

    less formal and less precise; used in general science writing instead of specialist chemistry contexts

Antonyms
  • anion

    the negatively charged counterpart of a cation

Usage Note

Opposed to anion, which is a negatively charged ion. This term appears mainly in chemistry and physics textbooks rather than everyday conversation.

Common Mistakes

A chloride ion is a cation.
A chloride ion is an anion.
Cations carry a positive charge; anions (such as chloride) carry a negative charge.

Word family

Synonym discussion

Sense: noun/1

Cation is the precise scientific term for a positively charged ion that moves toward the cathode during electrolysis. The phrase 'positive ion' is less formal and avoids the technical context of electrodes and electric current, making it suitable for general science explanations. The word 'anion' is the direct antonym and refers to a negatively charged ion that moves toward the anode. The main distinction is register: 'cation' is the standard term in chemistry textbooks and research papers, while 'positive ion' appears in introductory-level material. For example, a chemist would write 'calcium cations bind to the protein,' whereas a high-school textbook might say 'positive calcium ions attach to the protein.'

cation ↗positive ionanion ↗

Common collocations

Nouns

Phrases

  • form a cation
  • become a cation
  • act as a cation

Prepositions

Etymology

GreekEnglish

Coined by the English scientist Michael Faraday in the 1830s from the Greek words 'kata-' meaning 'down' and 'ion' meaning 'going.' Faraday used the term to describe the particle that moves downward (toward the cathode) when an electric current passes through a liquid.