Niobium , umwhile columbium , is a chemical element wi the seembol Nb (umwhile Cb ) an atomic nummer 41. It is a saft, grey, ductile transeetion metal, whilk is aften foond in the pyrochlore mineral, the main commercial soorce for niobium, an columbite. The name comes frae Greek meethology : Niobe , dauchter o Tantalus .
Niobium, 41 Niobium Pronunciation (ny-OH -bee-əm Appearance gray metallic, bluish when oxidized Standard atomic weight A r, std (Nb) 7001929063700000000♠ 92.90637 (1)[1] Niobium in the periodic cairt Atomic nummer (Z ) 41 Group group 5 Period period 5 Block d-block Element category Transeetion metalElectron confeeguration [Kr] 4d4 5s1 Electrons per shell 2, 8, 18, 12, 1 Pheesical properties Phase at STP solid Meltin pynt 2750 K (2477 °C, 4491 °F) Bylin pynt 5017 K (4744 °C, 8571 °F) Density (near r.t. ) 8.57 g/cm3 Heat o fusion 30 kJ/mol Heat o vapourisation 689.9 kJ/mol Molar heat capacity 24.60 J/(mol·K) Vapour pressur P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 2942 3207 3524 3910 4393 5013
Atomic properties Oxidation states −3, −1, +1, +2, +3, +4, +5 Electronegativity Pauling scale: 1.6 Ionisation energies 1st: 652.1 kJ/mol 2nd: 1380 kJ/mol 3rd: 2416 kJ/mol Atomic radius empirical: 146 pm Covalent radius 164±6 pm Colour lines in a spectral range Spectral lines o niobium Ither properties Naitural occurrence primordial Creestal structur cubic bouk-centred[[File:cubic bouk-centred|frameless|alt=Cubic bouk-centred creestal structur for niobium|upright=0.23|Cubic bouk-centred creestal structur for niobium]]
Speed o soond thin rod 3480 m/s (at 20 °C) Thermal expansion 7.3 µm/(m·K) Thermal conductivity 53.7 W/(m·K) Electrical resistivity 152 nΩ·m (at 0 °C) Magnetic orderin paramagnetic Young's modulus 105 GPa Shear modulus 38 GPa Bulk modulus 170 GPa Poisson ratio 0.40 Mohs haurdness 6.0 Vickers haurdness 870–1320 MPa Brinell haurdness 735–2450 MPa CAS Nummer 7440-03-1 History Namin after Niobe in Greek meethologie, dochter o Tantalus (tantalum) Diskivery Charles Hatchett (1801) First isolation Christian Wilhelm Blomstrand (1864) Recognised as a distinct element bi Heinrich Rose (1844) Main isotopes o niobium Isotope Abundance Hauf-life (t 1/2 ) Decay mode Product 90 Nbsyn 15 h β+ 90 Zr91 Nbsyn 680 y ε 91 Zr91m Nbsyn 61 d IT 91 Nb92m1 Nbsyn 10 d ε 92 Zrγ 92 Nbtrace 3.47×107 y ε 92 Zrγ 93 Nb100% stable 93m Nbsyn 16 y IT 93 Nb94 Nbtrace 20.3×103 y β− 94 Moγ 95 Nbsyn 35 d β− 95 Moγ 95m Nbsyn 4 d IT 95 Nb96 Nbsyn 24 h β− 96 Mo
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