Hafnium (Hf)
Silvery lustrous metallic transition element. Used in tungsten alloys in filaments and electrodes, also acts as a neutron absorber. First reported by Urbain in 1911, existence was finally established in 1923 by D. Coster, G.C. de Hevesy in 1923.
| Atomic Number | 72 |
|---|---|
| Atomic Weight | 178.49 |
| Mass Number | 180 |
| Group | 4 |
|---|---|
| Period | 6 |
| Block | d |
| Protons | 72 p+ |
|---|---|
| Neutrons | 108 n0 |
| Electrons | 72 e- |
Properties
| Atomic Radius | 155 pm
|
|---|---|
| Atomic Volume | 13.6 cm³/mol
|
| Covalent Radius | 152 pm
|
| Metallic Radius | 144 pm
|
| Ionic Radius | 58 pm
|
| Crystal Radius | 72 pm
|
| Van der Waals radius |
223 pm
|
| Density | 13.3 g/cm³
|
| Boiling Point | 5,470 K
|
| Melting Point | 2,503 K
|
| Electrons per shell | 2, 8, 18, 32, 10, 2 |
| Electronegativity |
1.3
|
| Electrophilicity | 0.8583981383413 eV/particle
|
| Proton Affinity | |
| Electron Affinity | 0.014 eV/particle
|
| Ionization Potential | 6.82507 eV/particle
|
| Heat of Vaporization | 575 kJ/mol
|
| Heat of Fusion | 25.1 kJ/mol
|
| Heat of Formation | 618.4 kJ/mol
|
| Molar Heat Capacity | 25.73 J/(mol K)
|
| Specific Heat Capacity | 0.144 J/(g⋅K)
|
| Thermal Conductivity | 23 W/(m K)
|
| Gas Basicity | |
| Dipole Polarizability | 103 a₀
|
| C6 Dispersion Coefficient | |
| Oxidation States | 2, 3, 4 |
| Color | Gray
|
| Crystal Structure | Simple Hexagonal (HEX) |
| Lattice Constant | 3.2 Å
|
| Bulk Modulus | |
| Electrical Resistivity | |
| Electron Configuration | [Xe] 4f14 5d2 6s2 |
| Magnetic Ordering | |
| Magnetic Susceptibility | |
| Phase | Solid |
| Poisson Ratio | |
| Shear Modulus | |
| Young's Modulus | |
| Allotropes | |
| Alternate Names | |
| Adiabatic Index | |
| Appearance | |
| Electric Conductivity | |
| Critical Pressure | |
| Critical Temperature | |
| Curie Point | |
| Electrical | |
| Hardness | |
| Magnetic Susceptibility | |
| Magnetic | |
| Neel Point | |
| Neutron Cross Section | |
| Neutron Mass Absorption | |
| Gas Phase | |
| Quantum Numbers | |
| Refractive Index | |
| Space Group | |
| Speed of Sound | |
| Superconducting Point | |
| Thermal Expansion | |
| Valence Electrons | |
| Classification | |
| Category | Transition metals, Transition metals |
| CAS Group | IVA |
| IUPAC Group | IVB |
| Glawe Number | 50 |
| Mendeleev Number | 45 |
| Pettifor Number | 50 |
| Geochemical Class | high field strength |
| Goldschmidt Class | litophile |
| Radioactivity | |
| Radioactive | No |
| Decay Mode | |
| Half-Life | |
| Lifetime | |
| Abundance | |
| Abundance in Earth's crust | 3 mg/kg
|
| Abundance in Oceans | 0.000007 mg/L
|
| Abundance in Human Body | |
| Abundance in Meteor | |
| Abundance in Sun | |
| Abundance in Universe | 7×10-8% |
Isotopes of Hafnium
Stable Isotopes
174Hf 176Hf 177Hf 178Hf 179Hf 180Hf
Unstable Isotopes
153Hf 154Hf 155Hf 156Hf 157Hf 158Hf 159Hf 160Hf 161Hf 162Hf 163Hf 164Hf 165Hf 166Hf 167Hf 168Hf 169Hf 170Hf 171Hf 172Hf 173Hf 175Hf 181Hf 182Hf 183Hf 184Hf 185Hf 186Hf 187Hf 188Hf
History
In 1911, Georges Urbain claimed to have found the element in rare-earth residues which was shown later to be a mixture of already discovered lanthanides. Dirk Coster and George de Hevesy found it by X-ray spectroscopic analysis in Norwegian zircon in 1922. Anton Eduard van Arkel and Jan Hendrik de Boer were the first to prepare metallic hafnium by passing hafnium tetra-iodide vapor over a heated tungsten filament in 1924. From Hafinia, the Latin name for Copenhagen
| Discoverers | Dirk Coster, Georg von Hevesy |
|---|---|
| Discovery Location | Denmark |
| Discovery Year | 1923 |
| Name Origin | From Hafnia, the Latin name of Copenhagen. |
Hafnium is considered to be non-toxic
In powdered form, hafnium is pyrophoric and can ignite spontaneously in air
Uses
Hafnium oxide-based compounds are being introduced into silicon-based chips to produce smaller, more energy efficient and performance packed processors. Most of the hafnium produced is used in the production of control rods for nuclear reactors. Hafnium is also used in photographic flash bulbs, light bulb filaments, and in electronic equipment as cathodes and capacitors. Used in reactor control rods because of its ability to absorb neutrons.
Sources
Obtained from mineral zircon or baddeleyite.