Iron (Fe)
Iron (Fe) is element 26, a transition metal. Atomic mass 55.845, configuration [Ar] 3d⁶ 4s². Properties, isotopes, oxidation states, uses and history, with an interactive 3D atom model.
Key facts
| Atomic number | 26 |
|---|---|
| Symbol | Fe |
| Standard atomic weight | 55.845(2) |
| Category | Transition Metal |
| Group | 8 |
| Period | 4 |
| State at room temperature | Solid |
| Electron configuration | [Ar] 3d⁶ 4s² |
| Valence electrons | 2 (Variable) |
| Common oxidation states | +2, +3 |
| Common ions | Fe²⁺, Fe³⁺ |
| Electronegativity (Pauling) | 1.83 |
| First ionization energy | 763 kJ/mol |
| Electron affinity | 14.57 kJ/mol |
| Atomic radius | 156 pm |
| Density | 7.87 g/cm³ |
| Melting point | 1538°C |
| Boiling point | 2861°C |
| Specific heat | 0.449 J/(g·°C) |
Natural isotopes
- Fe-54: Stable
- Fe-56: Stable
- Fe-57: Stable
- Fe-58: Stable
Common uses
- Construction (Steel)
- Vehicles
- Machinery
Where it matters
- Civilization development (Steel infrastructure)
- Biology (Hemoglobin/Oxygen transport)
Hazards
- Low toxicity
- acute overdose toxic
History
| Discovered | Prehistoric (~4000 BCE) |
|---|---|
| Discovered by | Ancient Civilizations (Iron Age) |
| Name | From Anglo-Saxon iren (Symbol Fe from Latin ferrum) |