Fe
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It has a standard atomic weight of 55.845, sits in period 4 and group 8, and is classified as a transition metal.
Properties
| Symbol | Fe |
|---|---|
| Atomic number | 26 |
| Standard atomic weight | 55.845 |
| Category | Transition metal |
| Group | 8 |
| Period | 4 |
| Electron configuration | [Ar] 3d6 4s2 |
| Outer-shell electrons | 2 |
The figure of 55.845 is a standard atomic weight.
Compounds containing iron
8 of the compounds in this reference contain Fe, listed by the fraction of their mass it makes up.
| Compound | Formula | Atoms | % by mass |
|---|---|---|---|
| hematite | Fe2O3 | 2 | 69.9% |
| iron oxide | FeO2 | 1 | 63.6% |
| pyrite | FeS2 | 1 | 46.6% |
| iron sulfate | FeO4S | 1 | 36.8% |
| iron chloride | Cl3Fe | 1 | 34.4% |
| potassium ferricyanide | C6FeK3N6 | 1 | 17.0% |
| potassium ferrocyanide | C6FeK4N6 | 1 | 15.2% |
| heme | C34H32FeN4O4 | 1 | 9.1% |
Calculate with iron
- Molar mass of any formula containing it
- Electron configuration, including ions
- Effective nuclear charge by Slater's rules
- Average atomic mass from isotope abundances
Group 8
Atomic weights are the IUPAC 2021 standard values, abridged to the conventional five significant figures. Group, period, category and electron configuration are derived from the atomic number rather than stored, so they cannot drift out of step with it.