Fe
Iron
Element 26 · Transition metal
Iron (Fe)
Iron is the most widely used metal and, by mass, the most common element on Earth, making up most of the planet’s core.
- Transition metal
- Period 4
- Group 8
- d-block
- solid at room temperature
Key properties
- Atomic mass
- 55.84
- u
- Electron configuration
- [Ar] 3d6 4s2
- Melting point
- 1,537.9 °C
- 1,811 K
- Boiling point
- 2,860.9 °C
- 3,134 K
- Density
- 7.874 g/cm³
- Electronegativity
- 1.83
- Pauling
- Atomic radius
- 194 pm
- van der Waals
- 1st ionisation energy
- 7.902 eV
Compare with every element:Electronegativity chartAtomic radius chartIonisation energy chartDensity chart of the elementsMelting point chartElectron configuration chart
Did you know?
Notable facts about iron
- 01
The earliest iron objects were made from meteorites.
- 02
Iron-56 nuclei are among the most stable; stars cannot release energy by fusing iron.
- 03
Haemoglobin uses iron to carry oxygen in your blood.
Applications
What is iron used for?
- Steel for buildings, cars and tools
- Cast iron cookware
- Magnets and transformers
- Dietary supplements
History
Discovery & name origin
Discovered by
Known since antiquity
Year
c. 5000 BCE
Where
Known since antiquity
Name origin
Anglo-Saxon iren; the symbol Fe comes from Latin ferrum.
Atomic structure
Atomic properties
Atomic structure
Atomic properties
- Atomic number
- 26
- Atomic mass
- 55.84 u
- Group
- 8
- Period
- 4
- Block
- d-block
- Electron configuration
- [Ar] 3d6 4s2
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d6
- Electrons per shell
- 2, 8, 14, 2
- Electronegativity (Pauling)
- 1.83
- Electron affinity
- 0.163 eV
- Atomic radius (van der Waals)
- 194 pm
- Stable isotopes
- 4
Oxidation states
Highlighted: common oxidation states (+3, +2).
Successive ionisation energies
Energy to remove each electron in turn (kJ/mol). Big jumps show where a new, inner shell begins.
- 1st762.5
- 2nd1,561.9
- 3rd2,957
- 4th5,290
- 5th7,240
- 6th9,560
- 7th12,060
- 8th14,580
Physical
Physical properties & colour
Physical
Physical properties & colour
- State at 20 °C
- Solid
- Melting point
- 1,811 K · 1,537.9 °C · 2,800.1 °F
- Boiling point
- 3,134 K · 2,860.9 °C · 5,181.5 °F
- Density
- 7.874 g/cm³
- Molar heat capacity
- 25.1 J/(mol·K)
- Appearance
- Lustrous metallic with a greyish tinge
- CPK model colour
- Copied
The CPK colour is the convention used for this element’s atoms in molecular models.
FAQ
Iron questions
What is Fe on the periodic table?
Fe is the symbol for iron, element 26 on the periodic table. It sits in group 8, period 4, in the transition metal category, and has an atomic mass of 55.84.
What is the atomic number of iron?
Iron has atomic number 26, so every iron atom has 26 protons in its nucleus. Its symbol is Fe and its atomic mass is 55.84.
Who discovered iron?
Iron has been known since antiquity (c. 5000 BCE); no single discoverer is credited. The name comes from Anglo-Saxon iren; the symbol Fe comes from Latin ferrum.
What is iron used for?
Iron is used for: steel for buildings, cars and tools; cast iron cookware; magnets and transformers; dietary supplements.
Is iron a metal?
Yes. Iron is a transition metal, one of the metallic elements.
What is the electron configuration of iron?
The electron configuration of iron is [Ar] 3d6 4s2. Its 26 electrons are arranged in shells as 2, 8, 14, 2.