Atomic number 26
Iron
Transition metal
Quick facts
- Atomic mass
- 55.845
- Group
- 8
- Period
- 4
- State (STP)
- solid
- Electronegativity
- 1.83
- Common ox. states
- +2, +3
Properties
Electron configuration
[Ar] 3d⁶ 4s²
- Ionization energy
- 762.5 kJ/mol
- Electron affinity
- 15.7 kJ/mol
- Melting point
- 1811.00 K (1537.8 °C)
- Boiling point
- 3134.00 K (2860.8 °C)
How it bonds
Iron toggles between Fe²⁺ (ferrous, pale green in water) and Fe³⁺ (ferric, yellow-brown — rust). The Fe²⁺/Fe³⁺ couple is what lets hemoglobin pick up and release O₂. Rust is hydrated Fe₂O₃; iron always loses to oxygen given time.
Element Lore
Stories, history, and chemistry behind Iron.
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