What is Fe2? Important knowledge about Fe2.

1. Definition of Fe₂
   Fe₂ is essentially the symbol for iron (II) ion, a form of ion of the chemical element Iron (Fe) with an oxidation number of +2.

1.1. Common name: Iron (II) ion
1.2. English name: Iron (II) ion
1.3. The atomic mass of iron is 55.85 u.
1.3.1. Molecular structure: The Fe₂+ ion has 24 electrons, 2 electrons less than the iron atom (Fe) as it has given up 2 electrons to form the Fe₂+ ion.
1.4. Ion structure: The Iron (II) ion has an electron configuration of [Ar]3d6, corresponding to the loss of 2 electrons in the outermost layer.

2. Properties of Fe₂
   2.1. Physical properties: Iron (II) ion is colorless, odorless and its pH cannot be measured as it does not exist in a soluble form in water.
   2.2. Chemical properties: Iron (II) ion can react with strong oxidizing agents to form Iron (III) ion.

3. Common chemical equations:
   3.1. Metallic reaction: Fe + CuSO₄ -> FeSO₄ + Cu
   3.2. Acid reaction: Fe + 2HCl -> FeCl₂ + H₂
   3.3. Non-metallic reaction: 2Fe + 3O₂ -> 2Fe₂O₃
   3.4. Reaction with salts: Fe + 2AgNO₃ -> Fe(NO₃)₂ + 2Ag

4. Synthesis of Fe₂:
   4.1. Laboratory synthesis: Fe₂+ can be synthesized from iron reacting with strong acids like HCl, H₂SO₄.
   4.2. Industrial synthesis: In industry, the iron (II) ion is synthesized through the oxidation of iron in an acidic environment.