Is iron(Fe) a diatomic molecule or a monatomic molecule?
Iron is a solid metal, therefore, it is a “gazillion-atomic” molecule. A piece of iron could be considered to be one giant “molecule” of iron. In a metallic substance each atom of the metal is covalently bonded to several adjacent metal atoms through a series of pi-bonds with highly delocalized electrons. This is why metals are good conductors of electricity. You can read up on the various allotropes of iron. Iron crystallizes in three different arrangements. Then there is the ability of iron to form “domains” where all of the spins of the electrons are aligned. This allows iron to become a permanent magnet. Each domain contains billions and billions of atoms. Therefore, there are NO individual “molecules” of iron in the solid state. If metallic iron was vaporized then you might get a “molecule” of some description. But iron vapor is not a common substance due to its very high boiling point.
