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Iron [Fe] – Element Details, History, Atomic Structure, Facts, Properties, Electronic Configuration, Atomic Spectrum, Uses.


Element 26 of Periodic table is Iron with atomic number 26, atomic weight 55.845. Iron, symbol Fe, has a Body Centered Cubic structure and Gray color. Iron is a Transition Metal element. It is part of group 8 (iron family). Know everything about Iron Facts, Physical Properties, Chemical Properties, Electronic configuration, Atomic and Crystal Structure.

History of Iron

The element Iron was discovered by Unknown in year Before 5000 BCE . Iron was first isolated by Egypt in 4000 BCE. Iron derived its name from English word (ferrum in Latin).

There is evidence that iron was known from before 5000 BCE. The oldest known iron objects used by humans are some beads of meteoric iron , made in Egypt in about 4000 BCE. The discovery of smelting around 3000 BCE led to the start of the iron age around 1200 BCE and the prominent use of iron for tools and weapons.

How to Locate Iron on Periodic Table

Periodic table is arranged by atomic number, number of protons in the nucleus which is same as number of electrons. The atomic number increases from left to right. Periodic table starts at top left ( Atomic number 1) and ends at bottom right (atomic number 118). Therefore you can directly look for atomic number 26 to find Iron on periodic table.

Another way to read periodic table and locate an element is by using group number (column) and period number (row). To locate Iron on periodic table look for cross section of group 8 and period 4 in the modern periodic table.

Iron Facts

Atomic Symbol
Atomic Number
Atomic Weight
Transition Metal
Group in Periodic Table
Group Name
iron family
Block in Periodic Table
Period in Periodic Table
Electronic Configuration
[Ar] 3d6 4s2
Melting Point
1811 K
Boiling Point
3134 K
Electronic Shell Structure
2, 8, 14, 2
CAS Number

Iron Atomic Structure and Orbital Properties

Iron atoms have 26 electrons and the electronic shell structure is [2, 8, 14, 2] with Atomic Term Symbol (Quantum Numbers) 5D4.

Element Properties

Atomic Number
Number of Protons
Mass Number
Number of Neutrons
Shell structure (Electrons per energy level)
2, 8, 14, 2
Electron Configuration
[Ar] 3d6 4s2
Valence Electrons
3d6 4s2
Oxidation State
-4, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7
Atomic Term Symbol (Quantum Numbers)

Atomic Structure of Iron

Atomic Radius
156 pm (1.56 Å)
Atomic Radius Empirical
140 pm (1.4 Å)
Atomic Volume
7.0923 cm3/mol
Covalent Radius
125 pm (1.25 Å)
Van der Waals Radius
Neutron Cross Section
Neutron Mass Absorption

Crystal Structure of Iron

The solid state structure of Argon is Face Centered Cubic.

The Crystal structure can be described in terms of its unit Cell. The unit Cells repeats itself in three dimensional space to form the structure.

The unit cell is represented in terms of its lattice parameters, which are the lengths of the cell edges Lattice Constants (a[286.65 pm]b[286.65 pm] and c[286.65 pm]) and the angles between them Lattice Angles (alpha[π/2], beta[π/2] and gamma[π/2])

The positions of the atoms inside the unit cell are described by the set of atomic positions ( xi, yi, zi) measured from a reference lattice point.

The symmetry properties of the crystal are described by the concept of space groups. All possible symmetric arrangements of particles in three-dimensional space are described by the 230 space groups (219 distinct types, or 230 if chiral copies are considered distinct.

Space Group Name

Space Group Number

Crystal Structure

Number of atoms per unit cell

Im_ 3m


Body Centered Cubic


Ground State Electronic Configuration of Iron- neutral Iron atom

Abbreviated electronic configuration of Iron

The ground state abbreviated electronic configuration of Neutral Iron atom is [Ar] 3d6 4s2. The portion of Iron configuration that is equivalent to the noble gas of the preceding period, is abbreviated as [Ar]. For atoms with many electrons, this notation can become lengthy and so an abbreviated notation is used. This is important as it is the Valence electrons 3d6 4s2, electrons in the outermost shell that determine the chemical properties of the element.

Unabbreviated electronic configuration of neutral Iron

Complete ground state electronic configuration for the Iron atom, Unabbreviated electronic configuration

1s2 2s2 2p6 3s2 3p6 3d6 4s2

Electrons are filled in atomic orbitals as per the order determined by the Aufbau principle, Pauli Exclusion Principle and Hund’s Rule.

  • As per the Aufbau principle the electrons will occupy the orbitals having lower energies before occupying higher energy orbitals. According to this principle, electrons are filled in the following order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p…
  • The Pauli exclusion principle states that a maximum of two electrons, each having opposite spins, can fit in an orbital.
  • Hund’s rule states that every orbital in a given subshell is singly occupied by electrons before a second electron is filled in an orbital.

Regulatory and Health - Health and Safety Parameters and Guidelines

RTECS Number
EU Number
DOT Hazard Class
DOT Numbers
NFPA Fire Rating
NFPA Hazards
Autoignition Point
NFPA Health Rating
NFPA Reactivity Rating
100 °C

Iron Chemical Properties : Iron Ionization Energies and electron affinity

15.7 kJ/mol

Iron Physical & Elastic Properties

7.874 g/cm3(when liquid at m.p density is $6.98 g/cm3)
Molar Volume
7.0923 g/cm3
Young Modulus
Shear Modulus
82 GPa
Bulk Modulus
170 GPa
Poisson Ratio

Iron Electrical Properties

Electrical Conductivity
10000000 S/m
9.7e-8 m Ω
Superconducting Point

Iron Magnetic Properties

Magnetic Type
Curie Point
1043 K
Mass Magnetic Susceptibility
Molar Magnetic Susceptibility
Volume Magnetic Susceptibility

Iron Thermal Properties

Melting Point
1811 K (1537.85°C, 2800.13 °F)
Boiling Point
3134 K (2860.85°C, 5181.53 °F)
Critical Temperature
Superconducting Point

Use of Iron

Iron is one of the most useful metal in the World. Mostly used to manufacture steel, constructions (reinforced concrete, girders etc) and in manufacturing. There are many different types of steel with different properties and uses.

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