I saw another exam question the answer to which I don't understand. The question was (among other things)
“what is the bonding between oxygen and magnesium in hydrate magnesium ion [Mg(H2O)6]2+?”
I wrote ligand but the provide answer is dative covalent.
I understand oxygen can provide (two) lone pairs of electrons. However, Magnesium is Group 2, period 3.
The order of energy levels is : 3s, 3p, 4s, 3d, with a big jump between 3p and 4s with a further jump to 3d.
Can the oxygen lone pairs (one pair from each of the six oxygens) form dative covalent bonds into the 3d orbital?