Kations

Kations are positively charged ions. In English the standard term is cation, with the plural cations; “Kations” is a transliteration sometimes used in other languages, though the typical English form is cation. They form when atoms or molecules lose electrons, leaving a net positive charge. Cations are attracted to negatively charged electrodes and combine with anions to form salts and other ionic compounds.

Cations can be monatomic, such as Na+, K+, and Ca2+, or polyatomic, such as ammonium NH4+. The common patterns align with oxidation state: alkali metals form +1 ions, alkaline earth metals form +2, and transition metals can exhibit multiple oxidation states (for example Fe2+ and Fe3+). The charge magnitude and the ionic radius influence properties such as hydration energy in solution and lattice energy in solids.

In aqueous solution, cations are typically surrounded by water molecules (hydration) and affect properties such as conductivity, pH, and electrostatic interactions with other species. They play essential roles in chemistry and biology: sodium, potassium, and calcium ions are crucial in nerve signaling and muscle function; ammonium participates in nitrogen metabolism; many metal cations act as catalysts or structural stabilizers in complexes and minerals.

Cations originate from salts and minerals, dissociating to yield positive ions like Na+, K+, Ca2+, and NH4+. They are central to electrochemistry, solution chemistry, and coordination chemistry, where their interactions with anions or ligands determine the behavior of substances in water, solids, and biological systems.