Lithium,  ₃Li

Lithium floating in oil
General properties
Pronunciation	/ˈlɪθiəm/ ​(LITH-ee-əm)
Appearance	silvery-white
Standard atomic weight (Ar, standard)	[6.938, 6.997]
Lithium in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson H ↑ Li ↓ Na helium ← lithium → beryllium
Atomic number (Z)	3
Group	group 1 (alkali metals)
Period	period 2
Block	s-block
Element category	alkali metal
Electron configuration	[He] 2s1
Electrons per shell	2, 1
Physical properties
Phase at STP	Li: Solid
Melting point	453.65 K ​(180.50 °C, ​356.90 °F)
Boiling point	1603 K ​(1330 °C, ​2426 °F)
Density (near r.t.)	0.534 g/cm3
when liquid (at m.p.)	0.512 g/cm3
Critical point	3220 K, 67 MPa (extrapolated)
Heat of fusion	3.00 kJ/mol
Heat of vaporization	136 kJ/mol
Molar heat capacity	24.860 J/(mol·K)
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 797 885 995 1144 1337 1610
Atomic properties
Oxidation states	+1 (a strongly basic oxide)
Electronegativity	Pauling scale: 0.98
Ionization energies	1st: 520.2 kJ/mol 2nd: 7298.1 kJ/mol 3rd: 11815.0 kJ/mol
Atomic radius	empirical: 152 pm
Covalent radius	128±7 pm
Van der Waals radius	182 pm
Spectral lines of lithium
Other properties
Natural occurrence	Li: Primordial
Crystal structure	​body-centered cubic (bcc)
Speed of sound thin rod	6000 m/s (at 20 °C)
Thermal expansion	46 µm/(m·K) (at 25 °C)
Thermal conductivity	84.8 W/(m·K)
Electrical resistivity	92.8 nΩ·m (at 20 °C)
Magnetic ordering	paramagnetic
Magnetic susceptibility	+14.2·10−6 cm3/mol (298 K)
Young's modulus	4.9 GPa
Shear modulus	4.2 GPa
Bulk modulus	11 GPa
Mohs hardness	0.6
Brinell hardness	5 MPa
CAS Number	7439-93-2
History
Discovery	Johan August Arfwedson (1817)
First isolation	William Thomas Brande (1821)
Main isotopes of lithium
Iso­tope Abun­dance Half-life (1/2) Decay mode Pro­duct 6Li 5% stable 7Li 95% stable
6Li content may be as low as 3.75% in natural samples. 7Li would therefore have a content of up to 96.25%.
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Lithium (from Greek lithos 'stone') is a soft, silver-white metal with symbol Li. It is the third chemical element in the periodic table. This means that it has 3 protons in its nucleus and 3 electrons around it. Its atomic number is 3. Its mass number is 6.94. It has two common isotopes, ⁶Li and ⁷Li. ⁷Li is more common; 92.5% of lithium is ⁷Li. Lithium is a soft silvery metal that is very reactive. It is used in lithium batteries and certain medicines.