A metallic → chemical element; symbol Li.
→ Atomic number 3;
→ atomic weight 6.941;
→ melting point about 180.54°C;
→ boiling point about 1,342°C.
Lithium is a soft, silver-white metal. It is the lightest
metal and one of the alkali metals in Group 1 of the → periodic table.
Lithium does not occur on Earth in its free form. It is a minor
part of almost all igneous rocks and is found in many natural brines,
in total 0.0007% of the Earth's crust. It has two stable
→ isotopes, 7Li (92.5%) and 6Li (7.5%).
The element was discovered in the mineral
petalite, LiAl(Si2O5)2, by the Swedish mineralogist Johan August
Arfwedson in 1817. It was isolated by W.T. Brande and Sir Humphrey
Davy. Many uses have been found for lithium and its compounds. Lithium
has the highest → specific heat (3.6 J/gK)
of any solid element and is used in heat transfer applications. It is used in
rechargeable lithium ion batteries. It is also used as an alloy with
→ aluminum, → copper, and
→ manganese to make high performance aircraft parts. It is
used to make special glasses and ceramics, including the Mount Palomar
telescope's 5 m mirror. Lithium also has various nuclear applications,
for example as a coolant in nuclear breeder reactors and a source of
→ tritium, which is formed by bombarding lithium with neutrons. In
medicine it is used to treat bipolar disorder (manic depression), a
serious mental illness that causes extreme shifts in mood, energy, and
Lithium, from L. lithos "stone" because lithium was thought to exist only in minerals.
lithium I line
xatt-e litiom I
Fr.: raie de lithium I
setâre-ye litiomi (#)
Fr.: étoile à lithium
A peculiar evolved star of spectral type G or M whose spectrum displays a high abundance of lithium.
Fr.: test du lithium
The presence or not of the lithium absorption line at 6708 Å, which is considered to be a sufficient condition for → substellarity in → L dwarfs. It has been shown that any object with lithium absorption and → effective temperature less than 2670 K is a → brown dwarf. For a discussion of potential problems with the lithium test see Kirkpatrick et al. (1993, ApJ 406, 701).