Lithium

Lithium (IPA: , from Greek: lithos: stone, because it was discovered in petalite) is a chemical element with the symbol Li and atomic number 3. It is in group 1 of the periodic table, among the alkali metals and is the least dense solid element.

Lithium in its pure form is a soft, silver white metal. It does not occur naturally on Earth in its elemental form. It reacts with oxygen from air to form white lithium oxide (Li2O). To prevent this oxidation reaction from occurring it is typically stored under the cover of oil. It tarnishes and oxidizes very rapidly in air and water. Lithium metal is used in rechargeable batteries (e.g. for cell phones and cameras), and in high strength to weight ratio alloys used for aircraft construction. Lithium compounds are used pharmacologically as a class of mood stabilizing drugs, a neurological effect of the lithium ion Li+.