Lithium

History

(Gr. lithos: stone) Discovered by Arfvedson in 1817. Arfvedson found the new element within the minerals spodumene and lepidolite in a petalite ore. The element was not isolated until W.T. Brande and Sir Humphrey Davy later used electrolysis on lithium oxide.

Properties

Lithium in its pure form is a soft, silver white metal, that tarnishes and oxidizes very rapidly in air and water. It is the lightest of all metals, with a density only about half that of water. Like all alkali metals, lithium reacts easily in water and does not occur freely in nature due to its activity. It is always found bound with one or more other elements or compounds. When placed over a flame, this metal gives off a striking crimson color but when it burns strongly, the flame becomes a brilliant white. This is also an univalent element.

Sources

Lithium is widely distributed but does not occur in nature in its free form. Combined, it is found in small units in nearly all igneous rocks and in  many mineral springs. Lepidolite, spodumene, petalite, and amblygonite are the more important minerals containing it.

Lithium is presently being recovered from brines of Searles Lake, in California, and from those in Nevada. Large deposits of quadramene are found in North Carolina. Since World War II, the production of lithium metal and its compounds has increased greatly. The metal is produced electrolytically from the fused chloride.

Uses

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 requires special handling. The metal has been used as an alloying agent, is of interest in synthesis of organic compounds, and has nuclear applications. It ranks as a leading contender as a battery anode material as it has a high electrochemical potential. Lithium is used in special glasses and ceramics. The glass for the 200-inch telescope at Mt. Palomar contains lithium as a minor ingredient.  

Lithium chloride is one of the most lyproscopic 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. Lithium carbide is used for the treatment of bipolar disease and other mental illness conditions.

Isotopes

Naturally occurring lithium is composed of 2 stable isotopes Li-6 and Li-7. Li-7 is the most abundant with 92.5% natural abundance. Six radioisotopes have been characterized with the most stable being Li-8 with a half-life of 838 ms and Li-9 with a half-life of 178.3 ms. All of the remaining radioactive isotopes have half-lifes that are less than 8.5 ms or are unknown.

Lithium-7, produced in the big bang nucleosynthesis, is one of the primordial elements. The isotopes fractionate substantially during a wide variety of natural processes, including metabolism, ion exchange, hyperfiltration, rock alteration and mineral formation.

Hazards

In its pure form, lithium is highly flammable and slightly explosive when exposed to air and especially water. This metal is also corrosive and requires special handling to avoid skin contact. When it is stored it should be placed in a non-reactive liquid hydrocarbon such as naphtha. Lithium plays no natural biological role and is considered to be slightly toxic. This means that when it is used as a drug, blood concentrations have to be carefully monitored.  

Lithium compounds are strongly basic and corrosive. Inhalation of these lithium compounds can cause severe irritation and corrosive tissue injury. Effects can include sore throat, coughing, shortness of breath and labored breathing. Severe exposures could cause serious lung injury such as edema and respiratory arrest, both leading to death. Upon contact, lithium can burn both the skin and eyes.  Ingestion can cause severe burning, sore throat, abdominal pain and vomiting leading to severe lung damage and finally death.