The element Lithium (Li) is found in period 2 and group 1 of the periodic table. Group 1 is also known as the alkali metal group and in addition to lithium includes sodium, potassium, rubidium, cesium and francium. It is a soft metal and can be cut with a knife.
All alkali metals react with water, but lithium is the least reactive of the group. Pure lithium can react with human skin and so must be handled with care. The pure silvery metal reacts with air to produce a coating of lithium hydroxide.
Lithium has the atomic number 3 and the atomic weight 6.941. According to Jefferson Labs Science education Lithium melts at 453.65 K (180.50°C or 356.90°F) and boils at 1615 K (1342° C or 2448°F). The density of this lightest of all metals is 0.534 grams per cubic centimeter. This is less than that of water and so the metal feels extremely lightweight.
As the element is so reactive, it is never found in its elemental state in nature. However, lithium compounds are relatively common. Webelements states that it forms a minor component of nearly all igneous rocks as well as being present in some naturally occurring brines. It forms 0.0007% of the Earth's crust.
According to the big bang theory for the start of the universe, lithium was one of the light elements formed within the first three minutes of the universe. The other elements formed at that time were hydrogen (deuterium) and helium. Heavier elements were produced within stars during the later evolution of the universe.
The name lithium is derived from the Greek word for stone "Lithos." Unlike sodium and potassium, which were originally found in plant material, lithium was first discovered in the mineral peralite. The element was recognized in this mineral in 1817 by Johan August Arfvedson. The production of a red flame by salts containing lithium was reported by C.G. Gmelin. While both Gmelin and Arfvedson studied lithium, they were unable to produce a pure sample of the element. Eventually a pure sample of the element was produced by Sir Humphrey Davy and W.T. Brande, using the electrolysis of lithium oxide.
Industrial production of lithium uses the electrolysis of a molten mixture of lithium chloride and potassium chloride. Pure lithium chloride melts at greater than 600°C. However, the mixture of lithium chloride and potassium chloride melts at around 430°C so the process is more energy efficient than using pure lithium chloride. This method of production was first suggested by Guntz in 1893. The first company to use this process was Metallgesellschaft AG, Germany in 1923. The ore spodumene is the most common source of the element and has to be processed through a number of reactions to produce the lithium chloride.
The low density of lithium makes it of use when alloyed with aluminum, copper manganese or cadmium to produce strong lightweight metals useful in aircraft manufacture. The New World Encyclopedia states that the specific heat capacity of lithium is extremely high at 3582 J/(kg·K). This is the highest value of any solid and so makes lithium useful in heat transfer processes.
Some lithium compounds have proved useful. Lithium carbonate is used in the treatment of some cases of bi-polar disorder. Owing to its potential toxicity, lithium treatment requires regular blood tests for lithium levels. Lithium hydroxide is used to remove excess carbon dioxide from the atmosphere within spacecraft. Another compound of use is lithium stearate, which is used as a lubricant and is useful as such at high temperatures.