Iron (Fe)
Earth's core is mostly iron, and iron is the most widely used metal by humans.
Iron properties
- Atomic mass
- 55.845 u
- Category
- Transition metal
- Group
- 8
- Period
- 4
- Block
- d-block
- State at room temp.
- Solid
- Electronegativity
- 1.83
- Melting point
- 1,811 K (1,537.8 °C)
- Boiling point
- 3,134 K (2,860.8 °C)
- Density
- 7.874 g/cm³
- Common charges
- +2, +3
- Oxidation states
- +3, +2
- Atomic radius
- 194 pm
- Ionization energy
- 7.902 eV
- Electron affinity
- 0.163 eV
- Radioactive
- No, has stable isotopes
- Discovered
- Ancient
Iron electron configuration
- Electron configuration
- [Ar] 3d6 4s2
- Full electron configuration
- 1s2 2s2 2p6 3s2 3p6 3d6 4s2
- Electron shells
- 2 · 8 · 14 · 2
The electron configuration of Iron (Fe) is [Ar] 3d6 4s2. Its 26 electrons are arranged in shells as 2, 8, 14, 2.
Protons, neutrons and electrons in Iron
A neutral Iron atom has 26 protons and 26 electrons. Most Iron atoms have about 30 neutrons: the atomic mass rounded to 56, minus the atomic number 26.
Neutrons are approximate: atoms of the same element can have different numbers of neutrons (isotopes). Atomic number and mass
How many valence electrons does Iron have?
2
Iron has 2 valence electrons, counting the electrons in its outermost s subshell. Like most transition metals, it can also use d electrons in bonding.
Iron orbital diagram
Each box is an orbital that holds up to two electrons with opposite spins (↑↓). The inner shells are the same as the noble gas in brackets. How to write electron configurations
Molar mass of Iron
55.845 g/mol
One mole of Iron atoms (6.022 × 10²³ atoms) has a mass of 55.845 grams. Use this value to convert between grams and moles.
Compounds containing Iron
Iron facts
- Earth's core is mostly iron, and iron is the most widely used metal by humans.
- Iron (Fe) has atomic number 26 and is a solid at room temperature. It has been known since ancient times.
Position in the periodic table
Iron is element 26, in period 4 and group 8 of the periodic table, in the d-block.
Uses of Iron
Iron is used mostly to make steel, an alloy of iron and a little carbon that forms the frames of buildings, bridges, cars and ships, as well as countless tools and machines. Cast iron is used for engine blocks, pipes and cookware. Iron catalysts are used to make ammonia for fertilizers, and iron oxides serve as pigments in paint, colored concrete and makeup.
Who discovered Iron?
Iron has been known since ancient times; the earliest iron objects, such as beads found in ancient Egyptian graves, were made from iron meteorites. People learned to smelt iron from ore more than 3,000 years ago, ushering in the Iron Age.
Where does the name come from?
Iron comes from the Old English iren (also isern), a word shared with other Germanic languages. Its symbol, Fe, comes from ferrum, the Latin word for iron, which also gives us words such as ferrous.
Same group
Compare Iron
FAQ
What is the electron configuration of Iron?
The electron configuration of Iron (Fe) is [Ar] 3d6 4s2. Its 26 electrons are arranged in shells as 2, 8, 14, 2.
How many protons, neutrons and electrons does Iron have?
A neutral Iron atom has 26 protons and 26 electrons. Most Iron atoms have about 30 neutrons: the atomic mass rounded to 56, minus the atomic number 26.
How many valence electrons does Iron have?
Iron has 2 valence electrons, counting the electrons in its outermost s subshell. Like most transition metals, it can also use d electrons in bonding.
What is the molar mass of Iron?
The molar mass of Iron is 55.845 g/mol. This is the same number as its atomic mass, 55.845 u.
Is Iron a metal?
Yes. Iron is a transition metal, so it is a metal.
Is Iron radioactive?
Ordinary Iron is not radioactive: it has at least one stable isotope. Like every element, it also has radioactive isotopes, most of them made in laboratories.
Where is Iron on the periodic table?
Iron is element 26, in period 4 and group 8 of the periodic table, in the d-block.