Iron

At a glance

Symbol

Fe

Atomic number

26

Average atomic mass

55.85

Group

8

Period

4

Family

transition metal

Electron configuration

[Ar] 3d⁶ 4s²

Electronegativity

1.83

Common ions

Fe²⁺ (iron(II)) and Fe³⁺ (iron(III))

Isotopes

⁵⁶Fe (91.8%), with smaller amounts of ⁵⁴Fe, ⁵⁷Fe and ⁵⁸Fe

On the table

Period 4, group 8. The other transition metals are tinted, and every cell opens its own article.

Electrons and bonding

Iron gives up two electrons to form Fe²⁺ or three to form Fe³⁺. Having two common ions is why its compounds are named with Roman numerals, as in iron(III) oxide.

Properties

State at 25 °C

solid

What it looks like

shiny gray metal that rusts in moist air

Melting point

1538 °C

Boiling point

2861 °C

Density

7.87 g/cm³

Magnetic

yes; iron, cobalt and nickel are the metals that are strongly magnetic at room temperature

Where it is found

By mass, the most abundant element in the Earth as a whole, because the core is mostly iron and nickel, and the fourth most abundant in the crust, about 5%. It is mined as hematite (Fe₂O₃) and magnetite (Fe₃O₄), above all in Australia and Brazil. Some meteorites are almost pure iron-nickel metal.

Discovery and name

Known since ancient times. The earliest iron objects were hammered from meteorites, and smelting iron from ore became widespread around 1200 BCE, beginning the Iron Age. The name is Old English; the symbol Fe comes from its Latin name, ferrum.