|
|
| Niobium | |
| Electron Configuration | 2,8,18,12,1 |
| Electron Configuration | [Kr] 4d4 5s1 |
| Ground state | |
| Atomic Volume | 10.87 g/cm3 |
| Electronegativity | 1.6 |
| Magnetic ordering | No data |
| Mass magnetic susceptibility | 2.81 x 10-8 |
| Molar magnetic susceptibility | 2.611 x 10-9 |
| Speed of sound | 3480 m s-1 |
 Thermal Properties |
|
| Enthalpy of Atomization | 745 kJ mol-1 @25°C |
| Enthalpy of Fusion | 27.2 kJ mol-1 |
| Enthalpy of Vaporisation | 680.19 kJ mol-1 |
| Heat Capacity | 24.60 J mol-1 K-1 |
| Thermal Conductivity | 53.7 W m-1 K-1 |
| Thermal Expansion | 7.3 μm m-1 K-1 |
| Hardness |
|
| Brinell hardness | 736 MPa |
| Mohs hardness | 6.0 |
| Vickers hardness | 1320 MPa |
| Elastic Properties |
|
| Bulk modulus | 170 GPa |
| Poisson ratio | 0.40 |
| Shear modulus | 38 GPa |
| Young's modulus | 105 GPa |
| Electrical Properties |
|
| Electrical resistivity | 1.5 x 10-7 Ω m |
| Electrical conductivity | No data. |
| Chemical Properties |
|
| Electrochemical Equivalent | 0.69327 g Ah-1 |
| Electron Work Function | 4.3 eV |
| Valence Electron Potential (-eV) | 104 |
| Ionization Potential | |
 First
|
6.88 |
| Second
|
14.32 |
| Third
|
25.04 |
| Energy Levels |
|
| Kα1 (intensity 100) |
16.6151 KeV |
| Kα2 (intensity 50) |
16.521 KeV |
| Kβ1 (intensity 16.8) |
18.6225 KeV |
| Kβ2 (intensity 3.4) |
18.9497 KeV |
| Kβ3 (intensity 7.9) |
18.6044 KeV |
| Lα1 (intensity 100) |
2.16589 KeV |
| Lα2 (intensity 10) |
2.163 KeV |
| Lβ1 (intensity 42.2) |
2.2574 KeV |
| Lβ2 (intensity 3.3) |
2.367 KeV |
| Lβ3 (intensity 4.4) |
2.3347 KeV |
| Lβ4 (intensity 4) |
2.3198 KeV |
| Lγ1 (intensity 4.2) |
2.4618 KeV |
| Lγ3 (intensity 2) |
1.996 KeV |
| Ll (intensity 5) |
1.9001 KeV |
| Atomic Radii |
|
| Empirical
|
145 pm |
| Bohr Radius
|
198 pm |
| Covalent Radius
|
137 pm |
| Van der Waals
|
No data. |
| Triple covalent
|
116 pm |
| Metallic
|
146 pm |
| Ionic Radii (Å) |
||||
| Charge | Coordination | Crystal | Ionic | Key |
| 3 | VI | 0.86 | 0.72 | |
| 4 | VI | 0.82 | 0.68 | RE |
| VIII | 0.93 | 0.79 | ||
| 5 | IV | 0.62 | 0.48 | C |
| VI | 0.78 | 0.64 | ||
| VII | 0.83 | 0.69 | C | |
| VIII | 0.88 | 0.74 | ||
| R, From r3 vs V plots. |
| C, Calculated from bond length - bond strength equations. |
| E, Estimated. |
| *, Most Reliable. |
| M, From Metallic Oxides. |
| A, Ahrens (1952) Ionic radius. |
| P, Pauling's (1960) Crystal Radius. |
| Oxidation States |
|
| Main
|
Nb+5 |
| Other
|
Nb-3, Nb-1, Nb+1, Nb+2, Nb+3, Nb+4 |
Ionisation Energies (kJ mol-1)  |
|
| M - M+ |
664 |
| M+ - M2+ |
1382 |
| M2+ - M3+ |
2416 |
| M3+ - M4+ |
3695 |
| M4+ - M5+ |
4877 |
| M5+ - M6+ |
9899 |
| M6+ - M7+ |
12100 |
| Vapour Pressure |
||||||
| P (Pa) | 1 | 10 | 100 | 1K | 10K | 100K |
| T (K) | 2949 | 3207 | 3524 | 3910 | 4393 | 5013 |
| Crystal Structure |
|
| Structure
|
Body centred cubic |
 |
a = 330.04 pm |
| b = 330.04 pm | |
| c = 330.04 pm | |
| α = 90° | |
| β = 90° | |
| γ = 90° | |