Hafnium (Hf)
Transition metal
Hafnium hid inside zirconium minerals for 130 years — the two elements are chemical near-twins. Their nuclear personalities differ completely: hafnium devours neutrons, making it perfect for reactor control rods.
Position on the periodic table
Atomic properties
| Atomic number | 72 |
|---|---|
| Atomic mass | 178.492 amu |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d2 |
| Noble gas shorthand | [Xe] 4f14 5d2 6s2 |
| Electrons per shell | 2, 8, 18, 32, 10, 2 |
| Valence electrons (outer shell) | 2 |
| Common oxidation states | +4 |
| Electronegativity (Pauling) | 1.3 |
| Covalent radius (approx.) | 175 pm |
| First ionization energy | 658.5 kJ/mol |
| Electron affinity | 17.2 kJ/mol |
Physical properties
| State at 25 °C | Solid |
|---|---|
| Density | 13.31 g/cm³ |
| Melting point | 2232.8 °C (2506 K) |
| Boiling point | 4602.9 °C (4876 K) |
| Appearance | steel gray |
| Radioactive | No |
| Origin | Occurs naturally |
Electron configuration of hafnium
Hafnium's ground-state electron configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d2, usually shortened to [Xe] 4f14 5d2 6s2. Its electrons occupy 6 shells (2, 8, 18, 32, 10, 2), placing it in period 6 of the d-block. Explore it interactively in the electron configuration calculator.
Uses of hafnium
- Nuclear submarine control rods
- Microchip gate insulators (HfO₂)
- Superalloys for jet engines
- Plasma cutting torch tips
Biological role: None known.
Occurrence: Always found within zirconium ores (about 1-4%).
Common compounds of hafnium
HfO2
Hafnium dioxide
History and discovery
Discovered: 1923 — Dirk Coster. Name origin: From Hafnia, the Latin name for Copenhagen, where it was discovered.
Dirk Coster and George de Hevesy found hafnium in 1923 in Copenhagen using X-ray spectroscopy — guided by Bohr's atomic theory.
Safety notes
Bulk metal is safe; powder is pyrophoric.
Educational context only — always follow your school's laboratory rules and never handle chemicals without proper supervision. See our disclaimer.
Practice questions
Quick practice: Hafnium
1. What is the chemical symbol of Hafnium?
2. What is the atomic number of Hafnium?
3. Which category does Hafnium belong to?
4. What is the state of Hafnium at room temperature?
5. Which period of the periodic table is Hafnium in?
Hafnium FAQs
What is the atomic number of hafnium?
Hafnium's atomic number is 72 — every hafnium atom has 72 protons in its nucleus.
What is the symbol for hafnium?
Hf. From Hafnia, the Latin name for Copenhagen, where it was discovered.
Is hafnium a metal, nonmetal, or metalloid?
Hafnium is classified as a transition metal.
What state is hafnium at room temperature?
At about 25 °C, hafnium is a solid. It melts at 2232.8 °C.
What is hafnium used for?
Key uses include: nuclear submarine control rods; microchip gate insulators (hfo₂); superalloys for jet engines.
Related elements
Keep working with this element
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