Lithium, Li

Lithium is a chemical element with the symbol Li and atomic number 3. It is a soft alkali metal with a silver-white colour. Under standard conditions, it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly reactive, corroding quickly in moist air to form a black tarnish. For this reason, lithium metal is typically stored under the cover of oil.

According to theory, lithium (mostly 7Li) was one of the few elements synthesized in the Big Bang, although its quantity has vastly decreased. The reasons for its disappearance and the processes by which new lithium is created continue to be important matters of study in astronomy. Lithium is the 33rd most abundant element on Earth, but due to its high reactivity only appears naturally in the form of compounds. Lithium occurs in a number of pegmatitic minerals, but is also commonly obtained from brines and clays; on a commercial scale, lithium metal is isolated electrolytically from a mixture of lithium chloride and potassium chloride.

Trace amounts of lithium are present in the oceans and in some organisms, though the element serves no apparent biological function in humans. Nevertheless, the neurological effect of the lithium ion Li+ makes some lithium salts useful as a class of mood stabilizing drugs. Lithium and its compounds have several other commercial applications, including heat-resistant glass and ceramics, high strength-to-weight alloys used in aircraft, and lithium batteries. Lithium also has important links to nuclear physics: the splitting of lithium atoms was the first man-made form of nuclear reaction, and lithium deuteride serves as the fusion fuel in staged thermonuclear weapons.

Technical Data
Symbol Li Density (20°C)/gcm-3 0.534
Atomic number 3 Melting point /°C 180.5
No. of naturally occurring isotopes 2 Boiling point /°C 1347
Atomic weight 6.941(+/- 3) ΔHfus/kJmol-1 2.93
Electronic configuration [He]2s1 ΔHvap/kJmol-1 148
Metal radius pm 152 ΔHf(monoatomic gas/kJmol-1 162
Ionic radius(6-coordinate)/pm 76 ΔHdissoc/kJmol-1 107.8
Ionization energy/kJmol-1 520.1 Eo(M+(aq)+ e- →M(S))/V -3.03
Evaporation Techniques
Temperature (oC) @Vap. Pressure Techniques Remarks
10-8 Torr 10-6 Torr 10-4 Torr Electron Beam Crucible Coil Boat
227 307 407 Good Al2O3 - Tantalum & Stainless steel Metal reacts violently in air

Evaporation Materials
L3-5000-M granules 3-6mm (under argon)
Rods
L3-2000-R 0.250" (6.35mm)
L3-2001-R 0.500" (12.7mm)