Lithium Li

Discovery

In 1817 the Swedish chemist Johan August Arfwedson, working in the laboratory of Jöns Jacob Berzelius, analysed the mineral petalite from the island of Utö and found that part of it behaved like an alkali but did not match sodium or potassium. He had discovered a new element, though he could not isolate the metal.

The first small samples of metallic lithium were obtained around 1821 by William Thomas Brande, who passed an electric current through lithium oxide. In 1855 Robert Bunsen and Augustus Matthiessen produced larger quantities by electrolysing molten lithium chloride, the basic method still used today. For about a century lithium remained a minor industrial metal, until nuclear weapons programmes, lubricating greases and finally lithium-ion batteries created huge demand.

Origin of the name

Berzelius proposed the name from the Greek lithos, meaning stone, because lithium was found in a mineral, whereas sodium and potassium had first been known from plant ashes. The symbol Li is taken from the first two letters.

Main uses

• Batteries: lithium-ion and lithium-polymer cells dominate portable electronics and electric vehicles; lithium primary cells power watches and medical implants.
• Glass and ceramics: lithium compounds lower melting temperatures and make heat-resistant cookware and glass-ceramic hobs.
• Greases: lithium soaps thicken lubricating greases that work over a wide temperature range.
• Alloys: aluminium–lithium alloys save weight in aircraft structures.
• Medicine: lithium carbonate has been used since the mid-twentieth century as a mood stabiliser for bipolar disorder, under careful medical monitoring.

Isotopes

Natural lithium consists of two stable isotopes: lithium-7, about 92 to 95 percent, and lithium-6, the remainder. Lithium-6 captures neutrons readily and produces tritium, which makes it important in nuclear technology and in the design of future fusion reactors. Lithium-7 is used in some reactor coolants. Radioactive isotopes of lithium are all very short-lived. Lithium is also one of the few elements made in the Big Bang, and the measured amount of lithium-7 in old stars is lower than models predict, a puzzle known as the cosmological lithium problem.

In everyday life

Lithium reacts with water to release hydrogen, though less violently than sodium, and it is stored under oil or inert gas. Damaged or overheated lithium-ion batteries can catch fire, which is why airlines restrict spare batteries in checked luggage.

Lithium is not an essential nutrient, but traces occur in drinking water. Most of the world's supply comes from hard-rock mines in Australia and from brine lakes in the salt flats of Chile, Argentina and Bolivia.