Tantalum
Tantalum, 73 Ta Pronunciation (TAN -tə-ləm ) Appearance gray blue Standard atomic weight A r, std (Ta) 180.94788 (2)[1]
Atomic number (Z ) 73 Group group 5 Period period 6 Block d-block Electron configuration [Xe ] 4f14 5d3 6s2 Electrons per shell 2, 8, 18, 32, 11, 2 Phase at STP 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
Oxidation states −3, −1, 0, +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 tantalumNatural occurrence primordial Crystal structure body-centered cubic (bcc)[2] α-Ta Crystal structure tetragonal[2] 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 [3] Molar magnetic susceptibility +154.0·10−6 cm3 /mol (293 K)[4] 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 Discovery Anders Gustaf Ekeberg (1802) Recognized as a distinct element by Heinrich Rose (1844)
Isotope
Abundance
Half-life (t 1/2 )
Decay mode
Product
177 Ta
syn
56.56 h
ε
177Hf
178 Ta
syn
2.36 h
ε
178Hf
179 Ta
syn
1.82 y
ε
179Hf
180 Ta
syn
8.125 h
ε
180Hf
β−
180W
180m Ta
0.012%
stable
181 Ta
99.988%
stable
182 Ta
syn
114.43 d
β−
182W
183 Ta
syn
5.1 d
β−
183W
Category: Tantalum | references
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.
Sources
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