Tantalum,  ₇₃Ta

General properties
Pronunciation	/ˈænələm/ ​(TAN-təl-əm)
Appearance	gray blue
Standard atomic weight (Ar, standard)	180.94788(2)
Tantalum 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 Nb ↑ Ta ↓ Db hafnium ← tantalum → tungsten
Atomic number (Z)	73
Group	group 5
Period	period 6
Block	d-block
Element category	transition metal
Electron configuration	[Xe] 4f14 5d3 6s2
Electrons per shell	2, 8, 18, 32, 11, 2
Physical properties
Phase at STP	Ta: Solid
Melting point	3290 K ​(3017 °C, ​5463 °F)
Boiling point	5731 K ​(5458 °C, ​9856 °F)
Density (near r.t.)	16.69 g/cm3
when liquid (at m.p.)	15 g/cm3
Heat of fusion	36.57 kJ/mol
Heat of vaporization	753 kJ/mol
Molar heat capacity	25.36 J/(mol·K)
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 3297 3597 3957 4395 4939 5634
Atomic properties
Oxidation states	−3, −1, +1, +2, +3, +4, +5 (a mildly acidic oxide)
Electronegativity	Pauling scale: 1.5
Ionization energies	1st: 761 kJ/mol 2nd: 1500 kJ/mol
Atomic radius	empirical: 146 pm
Covalent radius	170±8 pm
Spectral lines of tantalum
Other properties
Natural occurrence	Ta: Primordial
Crystal structure	​body-centered cubic (bcc) α-Ta
Crystal structure	​tetragonal β-Ta
Speed of sound thin rod	3400 m/s (at 20 °C)
Thermal expansion	6.3 µm/(m·K) (at 25 °C)
Thermal conductivity	57.5 W/(m·K)
Electrical resistivity	131 nΩ·m (at 20 °C)
Magnetic ordering	paramagnetic
Magnetic susceptibility	+154.0·10−6 cm3/mol (293 K)
Young's modulus	186 GPa
Shear modulus	69 GPa
Bulk modulus	200 GPa
Poisson ratio	0.34
Mohs hardness	6.5
Vickers hardness	870–1200 MPa
Brinell hardness	440–3430 MPa
CAS Number	7440-25-7
History
Discovery	Anders Gustaf Ekeberg (1802)
Recognized as a distinct element by	Heinrich Rose (1844)
Main isotopes of tantalum
Iso­tope Abun­dance Half-life (1/2) Decay mode Pro­duct 177Ta syn 56.56 h ε 177Hf 178Ta syn 2.36 h ε 178Hf 179Ta syn 1.82 y ε 179Hf 180Ta syn 8.125 h ε 180Hf β− 180W 180mTa 0.012% stable 181Ta 99.988% stable 182Ta syn 114.43 d β− 182W 183Ta syn 5.1 d β− 183W
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Tantalum in a glass tube

Tantalum is a chemical element. Tantalum was named tantalium. It has the chemical symbol Ta. It has the atomic number 73. It is a rare metal. It is hard and blue-gray. In chemistry it is placed in a group of metal elements named the transition metals.

Tantalum does not easily corrode. It is found in the mineral tantalite. view more...