Element 72 · Transition metal
Hafnium (Hf) — Element 72
Latin Hafnia — Copenhagen
Hafnium (Hf) is a transition metal in Period 6, Group 4 of the periodic table with atomic number 72, standard atomic weight 178.49 u, and ground-state electron configuration [Xe] 4f¹⁴ 5d² 6s². At standard temperature and pressure it is classified as a solid with 4 valence electrons and common oxidation states +4.
Nuclear control rods, microchips
What are the atomic properties and physical constants of Hafnium?
Reference constants compiled from IUPAC standard atomic weights, the NIST Atomic Spectra Database, and the CRC Handbook.
- Atomic number (Z)
- 72
- Standard atomic mass
- 178.49 u
- Chemical family
- Transition metal
- Ground-state configuration
- [Xe] 4f¹⁴ 5d² 6s²
- Electrons per shell
- 2, 8, 18, 32, 10, 2
- Valence electrons
- 4
- Common ion charges / oxidation states
- +4
- Phase at STP
- Solid
- Pauling electronegativity
- 1.30 Pauling
- First ionization energy
- 659 kJ/mol
- Atomic radius
- 208 pm
- Melting point
- 2,233 °C
- Boiling point
- 4,603 °C
- Discovery year
- 1923
- Table coordinate
- Period 6, Group 4
- Radioactivity
- Has stable isotope(s)
How are electrons arranged across Hafnium’s shells?
A neutral Hafnium atom contains 72 electrons distributed across 6 occupied principal energy shells ([Xe] 4f¹⁴ 5d² 6s²). The table below compares Hafnium’s shell occupancy against each shell’s theoretical 2n² capacity.
| Principal Shell (n) | Spectroscopic Letter | Electrons in Hf | Max Shell Capacity (2n²) |
|---|---|---|---|
| n = 1 | K | 2 e⁻ | 2 e⁻ |
| n = 2 | L | 8 e⁻ | 8 e⁻ |
| n = 3 | M | 18 e⁻ | 18 e⁻ |
| n = 4 | N | 32 e⁻ | 32 e⁻ |
| n = 5 | O | 10 e⁻ | 50 e⁻ |
| n = 6 | P | 2 e⁻ | 72 e⁻ |
Frequently Asked Questions about Hafnium (Hf)
What is the atomic mass and atomic number of Hafnium (Hf)?
Hafnium (Hf) has atomic number Z = 72 (72 protons in its nucleus) and an IUPAC standard atomic weight of 178.49 u. It sits in Period 6, Group 4 and is classified as a transition metal.
What is the ground-state electron configuration of Hafnium?
The neutral ground-state electron configuration of Hafnium (Z = 72) is [Xe] 4f¹⁴ 5d² 6s². Across its 6 occupied principal shells (n = 1 to n = 6), the electrons per shell are 2, 8, 18, 32, 10, 2, with 4 valence electrons participating in bonding.
What are the common ion charges and electronegativity of Hafnium?
Hafnium commonly forms +4 oxidation states or ion charges in compounds. Its Pauling electronegativity is 1.30 and its first ionization energy is 659 kJ/mol.
When was Hafnium discovered and what is it used for?
Hafnium was discovered in 1923 (Latin Hafnia — Copenhagen). Nuclear control rods, microchips
How does Hafnium compare to neighboring elements?
Other transition metal elements: