li

Li is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal and the lightest solid element at room temperature. Lithium is highly reactive and flammable in air, and it reacts vigorously with water to produce hydrogen gas and lithium hydroxide. It has a low density of 0.534 g/cm3, a melting point of 180.5°C, and a boiling point of 1342°C. In compounds, lithium is almost always in the +1 oxidation state.

Nature and production: Lithium occurs mainly in trace minerals and in brine pools. Major reserves exist in the Lithium Triangle (Chile, Argentina, Bolivia) and in Australia, China, and Canada. Commercial production combines mining of lithium-bearing minerals with brine extraction, followed by processing to battery-grade compounds such as Li2CO3 and LiOH for use in batteries, ceramics, and glass.

History: Lithium was discovered in 1817 by Johan August Arfwedson while analyzing the mineral petalite. The name derives from the Greek lithos, meaning stone.

Uses: The dominant modern use is in rechargeable lithium-ion batteries for portable electronics and electric vehicles, with lithium metal or compounds also employed in ceramics, glass, lubricants, and polymers. Medically, lithium salts are used as mood stabilizers for bipolar disorder.

Isotopes and safety: Two stable isotopes occur in nature, Li-6 and Li-7, with Li-7 comprising about 92.5%. Lithium is reactive and must be stored under oil; handling requires care to avoid ignition and environmental release.

Other meanings: Li is also a common surname and given name in East Asia, especially for the Chinese surname 李; the spelling appears in various romanizations and uses beyond science.