Iron
The backbone of industry and the core of our planet.
Inside the Iron atom
Switch between Bohr and Quantum Cloud modes to compare a simple teaching model with a more realistic probability-based view, and follow the guided tour to explore the Iron atom step by step.
Electron configuration
[Ar] 3d6 4s2
A neutral Iron atom has 26 electrons (equal to its proton count). Choosing a different isotope above changes only the neutron count.
Shell distribution
Electrons fill inner shells before outer ones; the outermost (valence) shell drives the element's chemistry.
Physical & atomic properties
- State (room temp)
- Solid
- Melting point
- 1811 K (1538 °C)
- Boiling point
- 3134 K (2861 °C)
- Density
- 7.874 g/cm³
- Electronegativity
- 1.83 Pauling
- Atomic radius
- 140 pm
- 1st ionization energy
- 762 kJ/mol
- Category
- Transition metals
Discovery & naming
- Discovered
- Antiquity
- Discovered by
- Known since antiquity
- Origin of name
- Anglo-Saxon 'iron'; symbol from Latin 'ferrum'.
Notable uses
Steel, construction, and the core of Earth and hemoglobin.
Where Iron comes from
Supernovae
Fusion builds it in massive-star cores, but supernovae — especially Type Ia — release most of the iron in the galaxy.
Simplified origin map — many elements form through more than one astrophysical pathway.
Summary
- Atomic number
- 26
- Atomic mass
- 55.845
- Category
- Transition metals
- Group · Period
- 8 · 4
- Block
- d-block
- Shells
- 2 · 8 · 14 · 2