Hafnium (Hf) – element 72
Hafnium is a chemical element with the symbol Hf and atomic number 72. It is a transition metal in group 4, period 6 of the periodic table (d-block), and is a solid at room temperature.
Hafnium (Hf) has atomic number 72, atomic mass 178.49 u and electron configuration [Xe] 4f14 5d2 6s2.
Hafnium facts
| Symbol | Hf |
|---|---|
| Atomic number | 72 |
| Atomic mass | 178.49 u (g/mol) |
| Category | transition metal |
| Group | group 4 |
| Period | 6 |
| Block | d-block |
| Phase at 20 °C | Solid |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d2 |
| Noble-gas notation | [Xe] 4f14 5d2 6s2 |
| Electrons per shell | 2, 8, 18, 32, 10, 2 |
Bohr model and shells
Hafnium has 72 electrons in 6 shells: 2, 8, 18, 32, 10, 2. Full configuration and noble-gas notation are in the table; work out any element or ion with the electron configuration calculator.
Physical and atomic properties
| Melting point | 2506 K (2232.8 °C) |
|---|---|
| Boiling point | 4876 K (4602.9 °C) |
| Density | 13.31 g/cm³ |
| Electronegativity (Pauling) | 1.3 |
| Electron affinity | 17.18 kJ/mol |
| Ionization energies | 658.5, 1440, 2250 kJ/mol (1st, 2nd, 3rd) |
| Molar heat capacity | 25.73 J/(mol·K) |
| Discovered by | Dirk Coster |
Use the atomic mass in the molar mass calculator for any formula containing Hf.
Position in the periodic table
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Frequently asked questions
What is the atomic mass of hafnium?
The atomic mass of hafnium is 178.49 u, so one mole of hafnium atoms weighs 178.49 g.
What is the electron configuration of hafnium?
Hafnium has 72 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d², or [Xe] 4f¹⁴ 5d² 6s² in noble-gas notation. Electrons per shell: 2, 8, 18, 32, 10, 2.
Is hafnium a metal?
Yes. Hafnium is a transition metal.
Where is hafnium on the periodic table?
Hafnium is in group 4, period 6, in the d-block.
Data: Periodic-Table-JSON (CC BY-SA 3.0); standard atomic weights from IUPAC (abridged). Values in brackets are the mass number of the longest-lived isotope.