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26 Fe 55.845(2)

Iron

Transition metal
Symbol Fe
Atomic Number 26
Atomic Weight 55.845(2)
CAS Registry ID 7439-89-6
Group Name (none)
Period Number 4
Block d-block
State at STP Solid

Description

Sample of Iron ⌕ Enlarge Image

Iron is one of the transition metals that has a gray metallic luster in its natural solid state. Iron is the most abundant element, 35% of the Earth’s mass is composed of iron, and it is one of the most used metals in the world. Iron has an atomic mass of 55.845, a melting point of 2800 °F, and a boiling point of 5182 °F. Iron is most commonly used in different types of metallic alloys for many various purposes.

Isolation

Iron is never found freely in nature, so various isolation purposes are used to isolate iron from minerals that it is found in.

Iron ⌕ Enlarge Image

Iron ore, such as hematite and magnetite, are where most of the iron that is used for industrial purposes comes from. Hematite is composed of the iron (III) oxide, and magnetite is composed of the iron (II, III) oxide. The iron is isolated from these minerals through a carbon reaction that is carried out in a blast furnace.

The furnace is heated to 3632 °F, coke which serves as the carbon source is added to furnace with the iron ore, and a flux like limestone is fed through the top of the furnace. Heated air is continually pushed into the bottom of the furnace to maintain the high temperatures. In the furnace, the coke and oxygen react to form carbon monoxide. The carbon monoxide reduce the iron ore resulting in pure iron and carbon dioxide. The limestone, or flux, melts other impurities inside the iron to further purify the iron ore.

General

NameIron
SymbolFe
Number26
Chemical seriesTransition metal
Group8
Period4
Blockd
Appearancelustrous metallic
Standard atomic weight55.845(2) g·mol⁻¹
Electron configuration[Ar] 4s2 3d6
Electrons per shell2, 8, 14, 2

Atomic Properties

Crystal structurebody-centered cubic
Oxidation states2, 3, 4, 6 (amphoteric oxide)
Electronegativity1.83 (Pauling scale)
Ionization energies1st: 762.5 kJ·mol−1
2nd: 1561.9 kJ·mol−1
3rd: 2957 kJ·mol−1
Atomic radius140 pm
Atomic radius (calc.)156 pm
Covalent radius125 pm
Van der Waals radius

Physical Properties

Phasesolid
Density (near r.t.)7.86 g·cm−3
Liquid density at m.p.6.98 g·cm−3
Melting point1811 K (1538 °C, 2800 °F)
Boiling point3134 K (2861 °C, 5182 °F)
Critical point
Heat of fusion13.81 kJ·mol−1
Heat of vaporization340 kJ·mol−1
Heat capacity(25 °C) 25.10 J·mol−1·K−1

Miscellaneous

Magnetic orderingferromagnetic
Electrical resistivity(20 °C) 96.1 nΩ·m
Thermal conductivity(300 K) 80.4 W·m−1·K−1
Thermal expansion(25 °C) 11.8 µm·m−1·K−1
Speed of sound (thin rod)(r.t.) (electrolytic) 5120 m·s−1
Young's modulus211 GPa
Shear modulus82 GPa
Bulk modulus170 GPa
Poisson ratio0.29
Mohs hardness4.0
Vickers hardness608 MPa
Brinell hardness490 MPa