72Hf178.492
Transition Metald-block
Hafnium
Element 72 on the periodic table, symbol Hf, group 4, period 6.
Hafnium is a chemical element with symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869, though it was not identified until 1923, making it the penultimate stable element to be discovered (rhenium was identified two years later).
Appearance: steel gray
Properties
- Atomic Number
- 72
- Atomic Mass
- 178.4920 u
- Group
- 4
- Period
- 6
- Block
- d-block
- Category
- Transition Metal
- State at 25 °C
- Solid
- Melting Point
- 2,506 K · 2,232.9 °C
- Boiling Point
- 4,876 K · 4,602.9 °C
- Density
- 13.31 g/cm³
- Atomic Radius
- 155 pm
- Electronegativity
- 1.3
- Oxidation States
- +4
- Abundance in Crust
- 3 mg/kg
- Discovered
- 1923
- Discovered By
- Dirk Coster
Electron Configuration
[Xe] 4f14 5d2 6s2
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d2
Ionisation Energies (kJ/mol)
- 1. 658.5
- 2. 1,440
- 3. 2,250
- 4. 3,216
Elements near Hafnium
Elements in the same group share the number of outer electrons and behave in similar ways. Elements in the same period share a shell, so they change steadily from left to right.