Definition of ion in English:



  • An atom or molecule with a net electric charge due to the loss or gain of one or more electrons.

    See also cation, anion
    • ‘Like the Solar Wind, the magnetosphere is full of plasma, consisting of ions and electrons.’
    • ‘Compounds that attach to metal ions by sharing their electrons are known as ligands.’
    • ‘Some compounds have polyatomic ions, where the ion is composed of two or more atoms.’
    • ‘The charge on the complex ion is the sum of the charges on the metal ion and the ligands.’
    • ‘Other atoms will shed or gain electrons, becoming electrically charged ions.’
    • ‘If just protons or sodium ions are present, the condition is not fulfilled and the logical molecule remains zeroed.’
    • ‘At that stage, the electrons and ions combined into neutral atoms that no longer scattered the radiation.’
    • ‘The hydrogen cation, one of the most common ions in the universe, is just a lone proton.’
    • ‘It creates electrically charged particles called corona ions which are carried away from the cable by the wind.’
    • ‘Switching off the electric field allows the ions to drop onto the silicon, where they bond to the surface in this pattern.’
    • ‘The ratio of ions in a formula unit depends on the charges of the ions in the compound.’
    • ‘The acidity of a substance is determined by how readily it donates hydrogen ions or protons.’
    • ‘A buffer is a system of chemicals that combines with an excess of hydrogen ions or hydroxide ions.’
    • ‘When he or she begins to perspire they will lose moisture as well electrolytes, or ions.’
    • ‘The reactant ions have enough energy to ionise the molecules of interest but not enough to break them up.’
    • ‘The net charge on an ion is denoted by a superscript showing both the size and charge.’
    • ‘You can take away the electron and make an ion, but you can't take away any neutrons.’
    • ‘The bacteria also release protons or hydrogen ions, which go into solution.’
    • ‘He discovered that power lines produce electrically charged particles called corona ions.’
    • ‘The methanol reacts with water in the presence of a catalyst to produce hydrogen ions and electrons.’


Mid 19th century: from Greek, neuter present participle of ienai go.