CHEMISTRY

Reviewed by GL:

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(From the name of Niobe, daughter of Tantalus, so named because this element was originally discovered in the tantalite). Metal gray, shiny, very ductile, refractory and resistant to corrosion is used in the manufacture of metal alloys for use in medicine, electronics and aerospace and nuclear industries. The niobium is a chemical element belonging to Group 5 of the periodic system, the group of transition metals (second series). Its chemical symbol is Nb, their number and atomic weight are, respectively, 41 and a 92.90638. It is a similar color to the metal nickel, less fusible than iron and hardness similar. Air, water and most regia acid does not affect normal temperature in hot and only reacts with oxygen, nitrogen, hydrogen and carbon. In nature are found in several minerals, usually associated with the tantalum, the most important columbite, has also been found in significant amounts in rocks silicocarbonatadas as pyrochlore.

An atomic mass: 92.90638 Melting point: 2741 K Boiling point: 5015 K Density: 8570kg / m³ Normal Reduction potential: - 0.65 V NB2 O5 | Nb acid solution Thermal Conductivity: 53.70 J / m s º C Electrical conductivity: 80.0 (mOhm.cm) -1 271.7 Specific heat J / kg K Heat of fusion: 27.2 kJ / mol Heat of Vaporization: 695.0 kJ / mol Heat of Atomization: 726.0 kJ / mol of atoms Oxidation states: -1, +2, +3, +4, +5 1st Ionization Energy: 663.8 kJ / mol 2nd Ionization Energy: 1381.7 kJ / mol 3rd Ionization Energy: 2416 kJ / mol Electronics affinity: 86.2 kJ / mol Radio Atómico: 1.46 Å Covalent radius: 1.34 Å Ionic Radius: +3 Nb = 0.71 Å +5 Nb = 0.70 Å Atomic volume: 10.87 cm ³ / mol Polarizability: 15.7 Å ³ Electronegativity(Pauling): 1.6