| Tecken | Hf |
| Atomnummer | 72 |
| Grupp | 4 (Titangruppen) |
| Period | 6 |
| Block | d |
| Ämnesklass | Övergångsmetall |
| Utseende | Steel gray |
| Färg | Grå |
| Antal protoner | 72 p+ |
| Antal neutroner | 106 n0 |
| Antal elektroner | 72 e- |
| Fas vid STP | Fast |
| Densitet | 13.31 g/cm3 |
| Relativ atommassa | 178.492 u |
| Smältpunkt | 2506 K 2232.85 °C 4051.13 °F |
| Kokpunkt | 4876 K 4602.85 °C 8317.13 °F |
| Ångbildningsvärme | 661.07 kJ/mol |
| Elektronegativitet (Paulingskalan) | 1.3 |
| Elektronaffinitet | 17.18 kJ/mol |
| Oxidationstal | −2, 0, +1, +2, +3, +4 (an amphoteric oxide) |
| Jonisationspotential |
|
| Förutsägelse | Dmitri Mendeleev (1869) |
| Upptäckt och första isolation | Dirk Coster, George de Hevesy (1922) |
Upptäckten av hafnium In his report on The Periodic Law of the Chemical Elements, in 1869, Dmitri Mendeleev had implicitly predicted the existence of a heavier analog of titanium and zirconium. The X-ray spectroscopy done by Henry Moseley in 1914 showed a direct dependency between spectral line and effective nuclear charge. This led to the nuclear charge, or atomic number of an element, being used to ascertain its place within the periodic table. With this method, Moseley determined the number of lanthanides and showed the gaps in the atomic number sequence at numbers 43, 61, 72, and 75. The discovery of the gaps led to an extensive search for the missing elements. And the reappearance in 1922 of Urbain's claims that element 72 was a rare earth element discovered in 1911, Dirk Coster and Georg von Hevesy were motivated to search for the new element in zirconium ores.Hafnium was discovered by the two in 1923 in Copenhagen, Denmark, validating the original 1869 prediction of Mendeleev. It was ultimately found in zircon in Norway through X-ray spectroscopy analysis. The place where the discovery took place led to the element being named for the Latin name for "Copenhagen", Hafnia, the home town of Niels Bohr. | |