Ions consisting of only a single atom are termed monatomic ions, atomic ions or simple ions, while ions consisting of two or more atoms are termed polyatomic ions or molecular ions.

Dec 26, 2025 · Ion, any atom or group of atoms that bears one or more positive or negative electrical charges. Positively charged ions are called cations; negatively charged ions, anions. …

Nov 20, 2021 · In chemical reactions, ions form when atoms or molecules gain or lose valence electrons. Only nuclear reactions change the number of protons in a chemical species. The …

Sep 4, 2019 · Learn the definition of an ion, as used in chemistry, chemical engineering, and physics, plus review examples of ions.

Nov 19, 2025 · Understand the fundamental chemistry of ions—charged atoms and molecules—that enable life, electricity, and crucial chemical reactions.

Jan 1, 2026 · Ions are atoms that have a positive or negative charge because they have unequal numbers of protons and electrons. If atoms lose electrons, they become positive ions, or cations.

Atoms can gain or lose electrons to form positively charged or negatively charged species called ions.