noun

ion

/ˈaɪən/ · say it: AI·uhn

an atom with an electrical charge from losing or gaining electrons

In Science & Nature

In more detail

1. (noun) an atom or group of atoms that has an electric charge because it has lost or gained one or more electrons

2. (noun) in chemistry, a particle that results from a chemical reaction and carries electrical charge

Examples

1. Salt dissolves in water into sodium and chloride ions.
2. The battery works by moving ions between its positive and negative terminals.

How to use ion

Ion is a technical term used primarily in chemistry and physics contexts. It refers specifically to an electrically charged particle formed when an atom or molecule gains or loses electrons. The term is neutral and objective, commonly appearing in scientific writing, textbooks, and laboratory discussions.

Common phrases

positive ion
negative ion
ion channel
ion exchange
hydrogen ion
sodium ion

Synonyms

charged particle · electrolyte particle · ionized atom

Word family

ionic (adjective) · ionize (verb) · ionization (noun) · ionized (adjective)

A common mistake

Learners sometimes confuse ions with atoms or molecules, not recognizing that ionization requires a change in electron count. Another common error is using 'ion' interchangeably with 'molecule' when the electrical charge is actually the defining feature.

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ion