what is lithium

Lithium is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal and has the lowest density of all metals. Lithium is highly reactive and flammable, and must be stored in vacuum, inert atmosphere, or inert liquid such as purified kerosene or mineral oil. Lithium is present in biological systems in trace amounts, but it has no established metabolic function. Lithium-based drugs are useful as a mood stabilizer and antidepressant in the treatment of mental illness such as bipolar disorder. Lithium is also used in the manufacture of aircraft and in certain batteries, including rechargeable batteries for mobile phones, laptops, digital cameras, and electric vehicles. It is also used in some non-rechargeable batteries for things like heart pacemakers, toys, and clocks. Lithium makes up a mere 0.0007 percent of the Earths crust.