Iron (Fe)
Transition metal
Iron is civilisation's metal — cheap, strong and endlessly versatile, it makes up most of the world's metal production as steel. Deep inside the Earth, a churning iron core generates our planet's magnetic field.
Position on the periodic table
Atomic properties
| Atomic number | 26 |
|---|---|
| Atomic mass | 55.8452 amu |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d6 |
| Noble gas shorthand | [Ar] 3d6 4s2 |
| Electrons per shell | 2, 8, 14, 2 |
| Valence electrons (outer shell) | 2 |
| Common oxidation states | +2, +3 |
| Electronegativity (Pauling) | 1.83 |
| Covalent radius (approx.) | 132 pm |
| First ionization energy | 762.5 kJ/mol |
| Electron affinity | 14.8 kJ/mol |
Physical properties
| State at 25 °C | Solid |
|---|---|
| Density | 7.874 g/cm³ |
| Melting point | 1537.8 °C (1811 K) |
| Boiling point | 2860.8 °C (3134 K) |
| Appearance | lustrous metallic with a grayish tinge |
| Radioactive | No |
| Origin | Occurs naturally |
Electron configuration of iron
Iron's ground-state electron configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d6, usually shortened to [Ar] 3d6 4s2. Its electrons occupy 4 shells (2, 8, 14, 2), placing it in period 4 of the d-block. Explore it interactively in the electron configuration calculator.
Uses of iron
- Steel for buildings, bridges, vehicles and machines
- Cast iron cookware and pipes
- Magnets and electrical transformers
- Catalyst in ammonia production
Biological role: Essential — the iron atom in haemoglobin carries oxygen through your blood.
Occurrence: About 5% of the crust; the Earth's core is mostly iron.
Common compounds of iron
Fe2O3
Iron(III) oxide (rust, hematite)
Fe3O4
Magnetite
FeSO4
Iron(II) sulfate
History and discovery
Discovered: Known since ancient times — 5000 BC. Name origin: From Old English iren; the symbol Fe comes from Latin ferrum.
Used for over 5,000 years, first from meteorites, then smelted from ore — the Iron Age is named after it.
Safety notes
Iron is safe in everyday forms; iron supplements in overdose are dangerous, especially for children.
Educational context only — always follow your school's laboratory rules and never handle chemicals without proper supervision. See our disclaimer.
Practice questions
Quick practice: Iron
1. What is the chemical symbol of Iron?
2. What is the atomic number of Iron?
3. Which category does Iron belong to?
4. What is the state of Iron at room temperature?
5. Which period of the periodic table is Iron in?
Iron FAQs
What is the atomic number of iron?
Iron's atomic number is 26 — every iron atom has 26 protons in its nucleus.
What is the symbol for iron?
Fe. From Old English iren; the symbol Fe comes from Latin ferrum.
Is iron a metal, nonmetal, or metalloid?
Iron is classified as a transition metal.
What state is iron at room temperature?
At about 25 °C, iron is a solid. It melts at 1537.8 °C.
What is iron used for?
Key uses include: steel for buildings, bridges, vehicles and machines; cast iron cookware and pipes; magnets and electrical transformers.
Related elements
Keep working with this element
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