26
Fe
Iron
55.845
Iron (Fe)
Transition MetalGroup 8Period 4d-block-block
Iron is a chemical element with symbol Fe (from Latin:ferrum) and atomic number 26. It is a metal in the first transition series. It is by mass the most common element on Earth, forming much of Earth's outer and inner core.
Latin name: Ferrum
Atomic Number
26
Atomic Mass
55.845 g/mol
Phase (STP)
Solid
Electron Config.
[Ar] 3d⁶ 4s²
General
SymbolFe
Atomic Number26
Atomic Mass55.845 g/mol
CategoryTransition Metal
Group8
Period4
Blockd-block
Electron Configuration[Ar] 3d⁶ 4s²
Valence Electrons2
ColourMetallic gray
Appearancelustrous metallic with a grayish tinge
CAS NumberCAS7439-89-6
Physical Properties
Phase (STP)Solid
Density7.874 g/cm³
Melting Point1537.85°C · 2800.13°F · 1811.00 K
Boiling Point2860.85°C · 5181.53°F · 3134.00 K
Atomic Properties
Atomic Radius156 pm
Covalent Radius132 pm
Van der Waals Radius194 pm
Electronegativity1.83 Pauling
Ionization Energy762 kJ/mol
Electron Affinity15.7 kJ/mol
Oxidation States-2, -1, +1, +2, +3, +4, +5, +6
Ion ChargeFe²⁺/Fe³⁺
Thermodynamic
Molar Heat25.1 J/(mol·K)
Thermal Conductivity80 W/(m·K)
Electromagnetic
Electrical TypeConductor
Electrical Conductivity10300000 S/m
Magnetic TypeFerromagnetic
Crystal Structure
Crystal StructureBody-centered cubic
Mechanical Properties
Mohs Hardness4
Abundance
In Universe0.1100%
In Sun0.0100%
In Earth's Crust5.6000%
In Oceans0.00003%
In Humans0.0060%
In Meteorites22.0000%
Discovery & History
Discovery Year-3500
Discovered ByKnown since antiquity
Isotopes of Iron
| Isotope | Abundance | Half-life | Decay |
|---|---|---|---|
| Fe-54 | 5.845% | Stable | — |
| Fe-56 | 91.754% | Stable | — |
| Fe-57 | 2.119% | Stable | — |
| Fe-58 | 0.282% | Stable | — |
| Fe-60 | — | 2.6 × 10⁶ years | β⁻ |