72178.49HfHafnium
Hafnium (Hf) — element 72transition metal · group 4, period 6
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 (the d-block), with a standard atomic mass of 178.49 u. At room temperature (25 °C) hafnium is a solid.
💡 Known for: Absorbs neutrons in nuclear control rods, and hafnium oxide insulates the transistors in modern chips.
# Hafnium properties
| Symbol | Hf |
|---|---|
| Atomic number | 72 |
| Atomic mass | 178.49 u |
| Category | transition metal |
| Group | 4 |
| Period | 6 |
| Block | d-block |
| Electron configuration | [Xe] 4f¹⁴ 5d² 6s² |
| Full configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d² 6s² |
| Electrons per shell | 2, 8, 18, 32, 10, 2 |
| Protons / electrons | 72 / 72 |
| State at 25 °C | solid |
| Melting point | 2506 K (2232.8 °C, 4051.1 °F) |
| Boiling point | 4876 K (4602.9 °C, 8317.1 °F) |
| Density | 13.31 g/cm³ |
| Electronegativity (Pauling) | 1.3 |
| First ionization energy | 6.825 eV |
| Atomic radius | 208 pm |
| Discovered | 1923 |
# Electron configuration of hafnium
The electron configuration of hafnium is [Xe] 4f¹⁴ 5d² 6s², written out in full as 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d² 6s². Its 72 electrons fill 6 shells as 2, 8, 18, 32, 10, 2, so the outermost shell holds 2 electrons.
# Related elements
LuLutetiumprevious elementTaTantalumnext elementTiTitaniumgroup 4ZrZirconiumgroup 4RfRutherfordiumgroup 4ScScandiumtransition metalVVanadiumtransition metalCrChromiumtransition metalMnManganesetransition metalFeIrontransition metalCoCobalttransition metalNiNickeltransition metalCuCoppertransition metal
# Hafnium FAQ
What is the atomic number of hafnium?
The atomic number of hafnium is 72: every hafnium atom has 72 protons in its nucleus. Its symbol is Hf.
What is the atomic mass of hafnium?
The standard atomic mass of hafnium is 178.49 u.
What is the electron configuration of hafnium?
Hafnium's electron configuration is [Xe] 4f¹⁴ 5d² 6s² (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d² 6s²), with 2, 8, 18, 32, 10, 2 electrons per shell.
Is hafnium a metal?
Yes. Hafnium is a transition metal, one of the metals.
What is the melting point of hafnium?
Hafnium melts at 2506 K (2232.8 °C, 4051.1 °F) and boils at 4876 K (4602.9 °C, 8317.1 °F).
What is hafnium used for / known for?
Absorbs neutrons in nuclear control rods, and hafnium oxide insulates the transistors in modern chips.