Iron (Fe)
Transition metal · d-block · period 4 · group 8
Lustrous grey metal; rusts red-brown in damp air.
Iron (symbol Fe) is chemical element number 26, a transition metal in group 8, period 4 of the periodic table. Its standard atomic weight is 55.845 and its electron configuration is [Ar] 3d6 4s2. At room temperature it is a solid. The most-used metal by far — about 90% of all metal refined worldwide.
Properties
| Atomic number | 26 |
|---|---|
| Atomic mass | 55.845 |
| Category | Transition metal |
| Block | d-block |
| Group · Period | 8 · 4 |
| Electron configuration | [Ar] 3d6 4s2 |
| Electrons per shell | 2, 8, 14, 2 |
| State at 25 °C | solid |
| Melting point | 1811 K |
| Boiling point | 3134 K |
| Density | 7.874 g/cm³ |
| Electronegativity (Pauling) | 1.83 |
| Radioactive | No |
| Origin | primordial |
| Discovered | Known since antiquity · Known since antiquity |
Key facts about Iron
- The most-used metal by far — about 90% of all metal refined worldwide.
- The Earth's core is mostly iron, and it is why the planet has a magnetic field.
- Haemoglobin uses an iron atom to carry oxygen in your blood.
- Made into steel by carefully controlling how much carbon it contains.
What Iron is used for
Steel for construction, vehicles, tools and machinery; magnets; catalysts; dietary supplements.
Where it sits in the periodic table
Iron is in group 8, period 4, of the d-block. Its electron configuration [Ar] 3d6 4s2 means its outermost shell holds 2 electrons, which is what places it here and explains much of its chemistry. See Iron on the interactive table →
Iron — frequently asked questions
What is Iron used for?
Steel for construction, vehicles, tools and machinery; magnets; catalysts; dietary supplements.
Is Iron radioactive?
No. Iron has at least one stable isotope and is not radioactive.
What is the electron configuration of Iron?
Iron has the electron configuration [Ar] 3d6 4s2, which is 2, 8, 14, 2 electrons per shell.
What group and period is Iron in?
Iron is in group 8, period 4, in the d-block. Its outer shell holds 2 electrons.
Who discovered Iron?
Iron has been known since ancient times.