Tantalum

hafnium ← tantalum → tungsten Nb ↑ Ta ↓ Db 73Ta Periodic table
Appearance
gray blue
General properties
Name, symbol, number	tantalum, Ta, 73
Pronunciation	/ˈtæntələm/ TAN-təl-əm; previously /tænˈtæliəm/ tan-TAL-ee-əm
Element category	transition metal
Group, period, block	5, 6, d
Standard atomic weight	180.94788 g·mol−1
Electron configuration	[Xe] 4f14 5d3 6s2
Electrons per shell	2, 8, 18, 32, 11, 2 (Image)
Physical properties
Phase	solid
Density (near r.t.)	16.69 g·cm−3
Liquid density at m.p.	15 g·cm−3
Melting point	3290 K, 3017 °C, 5463 °F
Boiling point	5731 K, 5458 °C, 9856 °F
Heat of fusion	36.57 kJ·mol−1
Heat of vaporization	732.8 kJ·mol−1
Specific heat capacity	(25 °C) 25.36 J·mol−1·K−1
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	5, 4, 3, 2, -1 (mildly acidic oxide)
Electronegativity	1.5 (Pauling scale)
Ionization energies	1st: 761 kJ·mol−1
	2nd: 1500 kJ·mol−1
Atomic radius	146 pm
Covalent radius	170±8 pm
Miscellanea
Crystal structure	body-centered cubic
Crystal structure note	α-Ta
Magnetic ordering	paramagnetic
Electrical resistivity	(20 °C) 131 nΩ·m
Thermal conductivity	(300 K) 57.5 W·m−1·K−1
Thermal expansion	(25 °C) 6.3 µm·m−1·K−1
Speed of sound (thin rod)	(20 °C) 3400 m/s
Young's modulus	186 GPa
Shear modulus	69 GPa
Bulk modulus	200 GPa
Poisson ratio	0.34
Mohs hardness	6.5
Vickers hardness	873 MPa
Brinell hardness	800 MPa
CAS registry number	7440-25-7
Most stable isotopes
Main article: Isotopes of tantalum
iso NA half-life DM DE (MeV) DP 177Ta syn 56.56 h ε 1.166 177Hf 178Ta syn 2.36 h ε 1.910 178Hf 179Ta syn 1.82 y ε 0.110 179Hf 180Ta syn 8.125 h ε 0.854 180Hf β− 0.708 180W 180mTa 0.012% >1.2×1015 y ε 0.929 180Hf β− 0.783 180W IT 0.075 180Ta α 2.103 176Lu 181Ta 99.988% 181Ta is stable with 108 neutrons 182Ta syn 114.43 d β− 1.814 182W 183Ta syn 5.1 d β− 1.070 183W

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.