Hafnium (Hf)
Element 72 · Transition metal · Solid at 25 °C · Group 4, Period 6
Hafnium soaks up neutrons, making it ideal for nuclear reactor control rods, and hafnium oxide layers sit inside modern computer chips.
On the periodic table, hafnium sits in group 4 in period 6. It is one of 38 elements classified as a transition metal, and at room temperature (25 °C) it is a solid.
Transition metals occupy the wide d-block in the middle of the table. As a family they are hard, dense, high-melting metals that conduct heat and electricity well. Their partly filled d-orbitals let many of them take several oxidation states, form vividly colored compounds, and act as catalysts — which is why so much of industry, and so much of biology, runs on this block.
Properties of hafnium
| Atomic number (Z) | 72 |
|---|---|
| Symbol | Hf |
| Atomic mass | 178.49 |
| Category | Transition metal |
| Group | 4 |
| Period | 6 |
| Block | d-block |
| Metal / nonmetal | Metal |
| State at 25 °C | Solid |
| Electron configuration | [Xe] 4f14 5d2 6s2 |
| Electronegativity (Pauling) | 1.3 |
| Melting point | 2,233 °C (2,506.15 K / 4,051.4 °F) |
| Boiling point | 4,603 °C (4,876.15 K / 8,317.4 °F) |
| Density | 13.31 g/cm³ |
Position in the periodic table
Hafnium shares group 4 with Titanium (Ti), Zirconium (Zr), Rutherfordium (Rf). Elements in the same group have the same number of outer electrons, so they tend to behave alike chemically — comparing them is one of the fastest ways to see periodic trends in action.
Within this dataset, its melting point is the #10 highest of the 102 elements with measured melting points.
Physical properties
Hafnium melts at 2,233 °C (2,506.15 K / 4,051.4 °F) and boils at 4,603 °C (4,876.15 K / 8,317.4 °F), giving it a liquid range of about 2,370 °C at standard pressure.
Its density is 13.31 g/cm³.
See also: the interactive periodic table, how to read the periodic table, periodic trends.