1. Electronic Configuration: Iron has an atomic number of 26, and its electronic configuration is [Ar]3d64s2. The '3d' orbitals play a crucial role in determining the valencies of transition metals.
2. Loss of Electrons: In order to achieve a stable noble gas configuration, iron atoms tend to lose electrons from the outermost '4s' orbital first, followed by the '3d' orbitals.
- +2 Valency: When iron loses its two '4s' electrons, it attains a +2 oxidation state, commonly known as ferrous iron (Fe2+). This involves the loss of the two electrons from the '4s' orbital.
- +3 Valency: In certain compounds, iron loses one more electron from the '3d' orbital in addition to the two '4s' electrons. This results in a +3 oxidation state, also called ferric iron (Fe3+). The removal of an additional electron from the '3d' orbital is less favorable, which explains why the +3 valency is less commonly observed.
The stability of these valencies is influenced by various factors such as electronegativity, ionic radii, ligand field effects, and the number of unpaired electrons. While iron primarily exhibits +2 and +3 oxidation states, it can also exhibit other less common valencies like +1, +4, and +6 in specific chemical environments or complexes.
