Iron · Fe Iron
The main element of steel; the iron in heme participates in oxygen transport.
- atomic number / Atomic number
- 26
- atomic weight / Atomic mass
- 55.84 u
- Family/Group
- 8
- Period · Block / Period · Block
- 4 · d
- Category / Category
- transition metal · Transition metal
- State / State
- solid state
- Electron configuration
- [Ar]4s2 3d6
- Oxidation states / Oxidation states
- +3, +2
- Electronegativity / Electronegativity
- 1.83（Pauling）
- Density / Density
- 7.874 g/cm³
- Melting point / Melting point
- 1811 K
- Boiling point / Boiling point
- 3134 K
- Atomic radius / Atomic radius
- 194 pm（van der Waals）
- First ionization energy
- 7.902 eV
- Discovery year / Discovery
- Ancient
attribute description and data source
properties taken from PubChem periodic table snapshot (2026-10-04). Atomic weights may be reference values or representative isotope masses and cannot be considered exact constants for all samples; density, phase transition points, and phase states depend on temperature, pressure, and allotropes. The solidification of helium requires pressure. Some properties of radioactive and superheavy elements are predicted values, and missing items are marked as not included. Please check the original source and experimental conditions for precise calculations.