Lithium, a metal, is the first element of the 2nd period. It is the lightest element of the alkali metals (Group IA). Other members of the group are sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).

Lithium was discovered by Arfwedson in 1817 while he was working in the laboratory of the 19th century Swedish chemist Berzelius.

The name lithium is derived from the Greek word, lithos, for stone, and the symbol Li is an abbreviation of that name.

It is the lightest of all the metals with a density = 0.534 g/cm³. In the solid state, the metal has a body-centered cubic structure like the rest of the alkali metals.

The abundance of lithium (and beryllium and boron) in the universe is much lower than that of the other 2nd period elements. The reason for this has to do with the mechanism of formation of the elements in stars.

One reason for this vigorous reactivity is that the element has the lowest ionization energy of the 2nd period elements.

Lithium does not occur free in nature; combined it is found in small amounts in nearly all igneous rocks and in the waters of many mineral springs. Lepidolite (a lithia mica), spodumene, petalite, and amblygonite are the more important minerals containing it.

Brande and also Davy were the first to isolate lithium metal, but significant quantities for study were not produced until 1855 by Bunsen and Mathiessen.

The metal is produced electrolytically from fused lithium chloride (just as are sodium, magnesium, aluminum, and others).

LiCl(liq) Li(liq) + ½ Cl₂(g)

Lithium is silvery in appearance, much like Na and K, two other members of the alkali metal series. It reacts with air, water, acids, and bases, but not as vigorously as sodium.

4Li(s) + O₂(g) Li₂O(s)

6Li(s) + N₂(g) 2Li₃N(s)

Li(s) + H₂O(liq) LiOH(aq) + ½ H₂(g)

Li(s) + HCl(aq) LiCl(aq) + ½ H₂(g)

Lithium imparts a beautiful crimson color to a flame and lithium salts are used in pyrotechnics. The metal burns strongly; the flame is a dazzling white.

Since World War II, the production of lithium metal and its compounds has increased greatly. Because the metal has the highest specific heat of any solid element, it has found use in heat transfer applications; however, it is corrosive and so requires special handling. The metal has been used as an alloying agent, and with magnesium it forms alloys having some of the highest strength-to-weight ratios of all known structural substances.

Organic compounds of lithium-such as ethyl lithium and butyl lithium-are used for preparing plastics and synthetic rubber.

Lithium is used as a fuel in the hydrogen bomb and as a radiation shield. Lithium salts are used in special glasses and ceramics; for example, the glass for the 200-inch telescope at Mt. Palomar contains lithium as a minor ingredient.

Lithium chloride is one of the most hygroscopic materials known, and it, as well as lithium bromide, is used in air conditioning and industrial drying systems. Lithium stearate is used as an all-purpose and high-temperature lubricant. Other lithium compounds are used in dry cells and storage batteries.