Chemistry

An Overview about the Chemical Element Lithium



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Lithium

Symbol: Li

Atomic Number: 3

Atomic Mass: 6.941 amu (atomic mass units)

Melting Point: 180.54 C (453.69 K, 356.972 F)

Boiling Point: 1347.0 C (1620.15 K, 2456.6 F)

Number of Protons: 3

Number of Electrons: 3

Number of Neutrons: 4

Classification: Metal

Group Name: Alkali Metal

Crystal Structure: Cubic

Density @ 293 K: 0.53 grams per cubic centimeter

Color: silver

Lithium was discovered in 1817 by the Swedish chemist Johan August Arfvedson. He was examining a sample of the mineral ore petalite. Although recognizing it as a new element he was unable to isolate it in a pure form. William Thomas Brande and Sir Humphrey Davy were the first to produce pure Lithium by electrolysis of Lithium oxide. The name Lithium is derived from the Greek "Lithos" which means stone. The other two Group one elements known at the time were potassium and sodium both of which had been isolated from plants so the stone reference apt as lithium was isolated from a mineral ore.

Lithium has never been found as a free element in nature. It is the least dense of all the metal elements. Lithium salts will impart a crimson red color to a flame however the metal burns with a bright white flame. Fresh lithium metal is silver in color but will quickly develop a grey tarnish if exposed to air. The element will react with water but not as violently as sodium and the other alkali metals.

There are two naturally occurring isotopes of lithium both of which are stable. Lithium-7 is the most abundant isotope at 92.41% the remaining being made up by lithium-6. Lithium also has seven unstable isotopes all with very short half lives the longest half life is that of lithium-8 at 838 milliseconds.

The first commercial production of lithium was made in Germany in 1923. Metallgesellschaft AG used electrolysis on a mixture of molten lithium chloride and potassium chloride. Since this the industrial uses for lithium and its compounds has grown.

* High performance alloys of lithium with aluminum, copper, manganese, and cadmium are used in aircraft production.

* A metal consisting of lead containing 0.04% lithium, 0.7% calcium and 0.6% sodium is known as Bahnmetall. This is used for making railroad bearings in Germany as it is harder than pure lead.

* It is used for the production of special glass and ceramics such as the Mount Palomar telescope's 200 inch mirror.

* Lithium hydroxide is used in the extraction of carbon dioxide from the cabins of aircraft and spacecraft

* Lithium chloride and lithium bromide are used in industrial drying and air conditioning systems.

* Lithium stearate is used as a lubricant. It is particularly useful for high temperature lubrication.

* It is used in the production of batteries.

* Lithium carbonate is used to treat bi-polar disorder.

* As it has a high specific heat it has uses in heat transfer applications.

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