Ion

Name:
Ion
Detailed information:
An atom or radical that has lost or gained one or more electrons and has thus acquired an electric charge. Positively charged ions are cations and those having a negative charge are anions. An ion often has entirely different properties from the element (atom) from which it was formed. In sodium chloride solution, sodium exists as sodium ion (Na⁺), i.e., sodium atoms that have lost one electron. The chlorine is present as chloride ion (Cl⁻), i.e., chlorine atoms that have gained one electron. Copper sulfate solution contains copper ion (Cu²⁺), i.e., copper atoms that have lost two electrons, and sulfate ion (SO₄²⁻), i.e., sulfate radicals that have gained two electrons. Ions occur in water solution or in the fused state (except in the case of gases). Compounds that form ions are called electrolytes because they enable the solution to conduct electricity. Ion formation causes an abnormal increase in the boiling point of water and also lowers the freezing point, the extent depending on the concentration of the solution. Ions are also formed in gases as a result of electrical discharge.See Ionization; Electrolysis; Ion Exchange.