Lithium, sodium and potassium all have important commercial uses. Caesium and rubidium have some uses, but are of greater interest to scientists than to industrialists, and francium, a radioactive element with short-lived isotopes, has no uses whatsoever.
Lithium is employed most widely in the form of lithium stearate, which is used in the thickening of industrial lubricants. Such lubricants are extremely resistant to water, and retain their properties at high temperatures. Lithium itself is employed as an alloying agent in lightweight, high-strength aluminium alloys used in the construction of aircraft. It is also a constituent of certain batteries.
About 60% of the sodium metal produced is used in the production of tetraethyl lead, an anti-knock agent added to motor fuel, although the movement towards unleaded petrol has reduced the demand for this compound. Like other alkali metals, sodium is a good reducing agent, and is used in the production of various metals, where it serves to reduce their chlorides.
The more expensive potassium is used less widely than sodium, although its compounds are important in the production of fertilizers, and in the photographic industry.
