Hf
Hafnium is a corrosion-resistant metal used in nuclear reactor control rods.
Physical Properties
| Atomic Mass | 178.49 u |
| Density | 13.31 g/cm³ |
| Melting Point | 2506.0 K |
| Boiling Point | 4876.0 K |
| Appearance | Steel gray metallic |
| State at Room Temp | Solid |
Chemical Properties
| Electronegativity | 1.3 (Pauling) |
| 1st Ionization Energy | 658.5 kJ/mol |
| Electron Affinity | 17.18 kJ/mol |
| Oxidation States | +2, +3, +4 |
Atomic Properties
| Electron Configuration | [Xe] 4f14 5d2 6s2 |
| Atomic Radius | 159.0 pm |
| Covalent Radius | 175.0 pm |
| Van der Waals Radius | 212.0 pm |
Discovery
| Discovered By | Dirk Coster, George de Hevesy |
| Discovery Year | 1923 |
| Location | Copenhagen, Denmark |
| Named After | Latin 'Hafnia' meaning Copenhagen |
About Hafnium
Hafnium is a lustrous, silvery gray metal chemically similar to zirconium. It is an excellent neutron absorber, in contrast to zirconium. Separating the two is critical for nuclear applications.
Uses & Applications
Nuclear reactor control rods, superalloys, microprocessor gate insulators (hafnium oxide), and plasma cutting tips.
Fun Fact
Hafnium and zirconium are so chemically similar they were not separated until 1923, yet their nuclear properties are opposite.
Isotopes
| Mass Number | Abundance | Half-Life | Stable |
| 177 | 0.186% | - | Yes |
| 178 | 0.2728% | - | Yes |
| 179 | 0.1362% | - | Yes |
| 180 | 0.3508% | - | Yes |
Electron Configuration
[Xe] 4f14 5d2 6s2