2655.845FeIron
Iron (Fe) — element 26transition metal · group 8, period 4
Iron is a chemical element with the symbol Fe and atomic number 26. It is a transition metal in group 8, period 4 of the periodic table (the d-block), with a standard atomic mass of 55.845 u. At room temperature (25 °C) iron is a solid.
💡 Known for: The most-used metal and the main ingredient of steel; it carries oxygen in blood and makes up most of Earth's core.
# Iron properties
| Symbol | Fe |
|---|---|
| Atomic number | 26 |
| Atomic mass | 55.845 u |
| Category | transition metal |
| Group | 8 |
| Period | 4 |
| Block | d-block |
| Electron configuration | [Ar] 3d⁶ 4s² |
| Full configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s² |
| Electrons per shell | 2, 8, 14, 2 |
| Protons / electrons | 26 / 26 |
| State at 25 °C | solid |
| Melting point | 1811 K (1537.8 °C, 2800.1 °F) |
| Boiling point | 3134 K (2860.8 °C, 5181.5 °F) |
| Density | 7.874 g/cm³ |
| Electronegativity (Pauling) | 1.83 |
| First ionization energy | 7.902 eV |
| Atomic radius | 156 pm |
| Discovered | known since ancient times |
# Electron configuration of iron
The electron configuration of iron is [Ar] 3d⁶ 4s², written out in full as 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s². Its 26 electrons fill 4 shells as 2, 8, 14, 2, so the outermost shell holds 2 electrons.
# Related elements
MnManganeseprevious elementCoCobaltnext elementRuRutheniumgroup 8OsOsmiumgroup 8HsHassiumgroup 8ScScandiumtransition metalTiTitaniumtransition metalVVanadiumtransition metalCrChromiumtransition metalNiNickeltransition metalCuCoppertransition metalZnZinctransition metalYYttriumtransition metal
# Iron FAQ
What is the atomic number of iron?
The atomic number of iron is 26: every iron atom has 26 protons in its nucleus. Its symbol is Fe.
What is the atomic mass of iron?
The standard atomic mass of iron is 55.845 u.
What is the electron configuration of iron?
Iron's electron configuration is [Ar] 3d⁶ 4s² (1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁶ 4s²), with 2, 8, 14, 2 electrons per shell.
Is iron a metal?
Yes. Iron is a transition metal, one of the metals.
What is the melting point of iron?
Iron melts at 1811 K (1537.8 °C, 2800.1 °F) and boils at 3134 K (2860.8 °C, 5181.5 °F).
What is iron used for / known for?
The most-used metal and the main ingredient of steel; it carries oxygen in blood and makes up most of Earth's core.