Discovery date : 1923
Discovered by: George Charles de Hevesy and Dirk Coster
Origin of the name: The name is derived from the Latin name for Copenhagen, 'Hafnia'
Allotropes :
~>HAFNIUM is a chemical element with symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals.
| FACT BOX | |||
| Group | 4 | Melting point | 2233°C, 4051°F, 2506 K |
| Period | 6 | Boiling point | 4600°C, 8312°F, 4873 K |
| Block | d | Density (g cm−3) | 13.3 |
| Atomic number | 72 | Relative atomic mass | 178.49 |
| State at 20°C | Solid | Key isotopes | 177Hf,178Hf,180Hf |
| Electron configuration | [Xe] 4f145d26s2 | CAS number | 7440-58-6 |
| ChemSpider ID | 22422 | ChemSpider is a free chemical structure database | |
In 1911, Georges Urbain reported the discovery of the missing element below zirconium in the periodic table, but he was wrong and the search continued. It was finally discovered by George Charles de Hevesy and Dirk Coster at the University of Copenhagen in 1923. It was found in a zirconium mineral, a Norwegian zircon, but it had proved very difficult to separate it from zirconium and this explained why hafnium remained undiscovered for so long.
Other zirconium minerals were now examined by Hevesy, and some were found to contain as much as five per cent of hafnium. (It meant the atomic weight of zirconium was wrong and hafnium-free material had to be produced in order for this to be determined.)
The first pure sample of hafnium itself was made in 1925 by decomposing hafnium tetra-iodide over a hot tungsten wire.