Final answer:
The process of converting metallic iron to the ferrous state is known as oxidation, which involves the loss of electrons and an increase in the oxidation number from 0 to +2. This is exemplified in the transition from the electron configuration of iron from Fe¹⁰ to Fe²⁰.
Step-by-step explanation:
The conversion of metallic iron (Fe0) to the ferrous state (Fe2+), in which the iron atom loses a pair of electrons, thereby attaining a more positive state, is said to be oxidation. The oxidation number of iron increases from 0 in the metallic state to +2 in the ferrous state. This process involves the removal of electrons, typically during a reaction with a nonmetal such as oxygen, as demonstrated in the reaction 4Fe(s) + 3O2(g) → 2Fe2O3 (s), where iron has an oxidation number of +3 in Fe2O3.
In transition metals like iron, the electrons are usually removed from the 4s orbital when forming positive ions like Fe2+ and Fe3+. An example of the electronic configuration change for Fe2+ is from 1s22s22p63s23p64s23d6 to 1s22s22p63s23p63d6, indicating the loss of two 4s electrons.