Ion

An ion is an atom or molecule with a net electric charge because it has gained or lost electrons. Positively charged ions are cations; negatively charged ions are anions.

Cation: A positively charged ion formed when an atom or molecule loses electrons. Electron loss leaves the ion with more protons than electrons.
Electric charge: A fundamental property of matter that determines its electromagnetic interactions. An ion's net charge is the defining result of an imbalance between positive and negative charge.
Electrolyte: A substance that produces mobile ions when dissolved or melted and conducts electricity through them. Its mobile ions carry current through solutions and molten materials.
Molecule: A group of atoms held together by chemical bonds and acting as a unit. A molecule can be neutral or charged; a charged molecule is a molecular ion.
Anion: A negatively charged ion formed when an atom or molecule gains electrons. Electron gain leaves the ion with more electrons than protons.
Electron: A negatively charged subatomic particle found in atoms and molecules. Ions form when electrons are transferred or, in some cases, removed.
Electrolysis: A process that uses electric current to drive a nonspontaneous chemical reaction. Ions move to electrodes and participate in the reactions driven by current.
Ion pair: A pair of oppositely charged ions held together by electrostatic attraction. It shows how separate ions can associate without becoming a neutral molecule.
Ionization: The process by which atoms or molecules become ions through electron loss or gain. It describes how neutral particles acquire the charge that defines ions.
Proton: A positively charged particle in an atomic nucleus. Protons provide the positive charge against which an ion's electrons are counted.

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