| Atomic number | 26 | | Atomic mass | 55.85 g.mol -1 | | Electronegativity according to Pauling | 1.8 | | Density | 7.8 g.cm-3 at 20°C | | Melting point | 1535.0 °C (1808.15 K, 2795.0 °F) | | Boiling point | 2750.0 °C (3023.15 K, 4982.0 °F) | | Vanderwaalsradius | 0.126 nm | | Ionic radius | 0.076 nm (+2) ; 0.064 nm (+3) | | Isotopes | 8 | | Electronic shell | [ Ar ] 3d6 4s2 | | Energy of first ionisation | 761 kJ.mol -1 | | Energy of second ionisation | 1556.5 kJ.mol -1 | | Energy of third ionisation | 2951 kJ.mol -1 | | Standard potential | - o.44 V (Fe2+/ Fe ) ; 0.77 V ( Fe3+/ Fe2+ ) | | Discovered by | The ancients |
Iron is a lustrous, ductile, malleable, silver-gray metal (group VIII of the periodic table). It is known to exist in four distinct crystalline forms. Iron rusts in dump air, but not in dry air. It dissolves readily in dilute acids. Iron is chemically active and forms two major series of chemical compounds, the bivalent iron (II), or ferrous, compounds and the trivalent iron (III), or ferric, compounds.
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