Iron (Fe) - Element 26 | Properties & Electron Configuration
What is Iron?
Iron (Fe) is element 26, a transition metal in period 4, group 8. Its electron configuration is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s².
| Atomic Number | 26 |
| Symbol | Fe |
| Atomic Mass | 55.845 u |
| Category | Transition Metal |
| Period | 4 |
| Group | 8 |
| Block | d |
| Electron Configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s² |
| Short Config | [Ar] 3d⁶ 4s² |
| Electronegativity | 1.83 |
| Atomic Radius | 126 pm |
| Ionization Energy | 762 kJ/mol |
| Electron Affinity | 15 kJ/mol |
| Phase (STP) | Solid |
Electron Configuration
The full electron configuration of Iron is 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s². In noble gas shorthand, this is written as [Ar] 3d⁶ 4s².
Iron is a d-block element in group 8, period 4.
Periodic Trends
Electronegativity: Iron has a Pauling electronegativity of 1.83. Within group 8, electronegativity generally decreases down the group.
Atomic Radius: 126 pm. Across period 4, atomic radius generally decreases left to right as nuclear charge increases.
Ionization Energy: 762 kJ/mol. Ionization energy generally increases across a period and decreases down a group.
View all 118 elements with trend overlays for electronegativity, atomic radius, ionization energy, and electron affinity.
Explore Iron on the Interactive Periodic TableRelated Topics
Ruthenium (Ru)
Properties of Ruthenium - same group as Iron
Osmium (Os)
Properties of Osmium - same group as Iron
Hassium (Hs)
Properties of Hassium - same group as Iron
Potassium (K)
Properties of Potassium - same period as Iron
Calcium (Ca)
Properties of Calcium - same period as Iron
Scandium (Sc)
Properties of Scandium - same period as Iron