|
|
| Cobalt | |
| Electron Configuration | 2,8,15,2 |
| Electron Configuration | [Ar] 3d7 4s2 |
| Ground state | 4F9/2 |
| Atomic Volume | 6.7 g/cm3 |
| Electronegativity | 1.88 |
| Magnetic ordering | Ferromagnetic |
| Speed of sound | 4720 m s-1 |
 Thermal Properties |
|
| Enthalpy of Atomization | 26.8 kJ mol-1 @25°C |
| Enthalpy of Fusion | 15.2 kJ mol-1 |
| Enthalpy of Vaporisation | 382.4 kJ mol-1 |
| Heat Capacity | 24.81 J mol-1 K-1 |
| Thermal Conductivity | 100 W m-1 K-1 |
| Thermal Expansion | 13 μm m-1 K-1 |
| Hardness |
|
| Brinell hardness | 700 MPa |
| Mohs hardness | 5.0 |
| Vickers hardness | 1043 MPa |
| Elastic Properties |
|
| Bulk modulus | 180 GPa |
| Poisson ratio | 0.31 |
| Shear modulus | 75 GPa |
| Young's modulus | 209 GPa |
| Electrical Properties |
|
| Electrical resistivity | 6 Ω m |
| Electrical conductivity | No data. |
| Chemical Properties |
|
| Electrochemical Equivalent | 1.0994 g Ah-1 |
| Electron Work Function | 5 eV |
| Valence Electron Potential (-eV) | 38.7 |
| Ionization Potential | |
 First
|
7.86 |
| Second
|
17.06 |
| Third
|
33.5 |
| Incompatibilities | Strong oxidizers, ammonium nitrate (NH4NO3). |
| Flammability |
|
| Non-combustible solid (except as dust)
|
| Energy Levels |
|
| Kα1 (intensity 100) |
6.93032 KeV |
| Kα2 (intensity 50) |
6.9153 KeV |
| Kβ1 (intensity 20) |
7.64943 KeV |
| Lα1 (intensity 100) |
0.7762 KeV |
| Lα2 (intensity 10) |
0.7762 KeV |
| Lβ1 (intensity 24.1) |
0.7914 KeV |
| Lβ3 (intensity 3) |
0.866 KeV |
| Lβ4 (intensity 0.5) |
0.866 KeV |
| Lγ3 (intensity 13) |
0.694 KeV |
| Ll (intensity 40) |
0.6773 KeV |
| Atomic Radii |
|
| Empirical
|
135 pm |
| Bohr Radius
|
152 pm |
| Covalent Radius
|
126 pm |
| Van der Waals
|
No data. |
| Triple covalent
|
96 pm |
| Metallic
|
125 pm |
| Ionic Radii (Å) |
||||
| Charge | Coordination | Crystal | Ionic | Key |
| 2 | IV (High spin) | 0.72 | 0.58 | |
| V | 0.81 | 0.67 | C | |
| VI (High spin) | 0.885 | 0.745 | R* | |
| VI (Low spin) | 0.79 | 0.65 | R | |
| VIII | 1.04 | 0.9 | ||
| 3 | VI (High spin) | 0.75 | 0.61 | |
| VI (Low spin) | 0.685 | 0.545 | R* | |
| 4 | IV | 0.54 | 0.4 | |
| VI (High spin) | 0.67 | 0.53 | R | |
| 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
|
Co+2 |
| Other
|
Co-1, Co0, Co+1, Co+3, Co+4, Co+5 |
Ionisation Energies (kJ mol-1)  |
|
| M - M+ |
760 |
| M+ - M2+ |
1646 |
| M2+ - M3+ |
3232 |
| M3+ - M4+ |
4950 |
| M4+ - M5+ |
7670 |
| M5+ - M6+ |
9840 |
| M6+ - M7+ |
12400 |
| M7+ - M8+ |
15100 |
| M8+ - M9+ |
17900 |
| M9+ - M10+ |
26600 |
| Vapour Pressure |
||||||
| P (Pa) | 1 | 10 | 100 | 1K | 10K | 100K |
| T (K) | 1790 | 1960 | 2165 | 2423 | 2755 | 3198 |
| Crystal Structure |
|
| Structure
|
Hexagonal close packed |
 |
a = 250.71 pm |
| b = 250.71 pm | |
| c = 406.95 pm | |
| α = 90° | |
| β = 90° | |
| γ = 120° | |