Statement I: Metal ions are Lewis acids. Statement II : Metal ions are electron pair acceptors.

According to the Lewis theory of acids and bases, a Lewis acid is defined as any chemical species (atom, ion, or molecule) that acts as an electron-pair acceptor [1]. Metal ions, particularly cations like Al3+ or transition metal ions, possess empty valence orbitals or an incomplete octet, which allows them to accept nonbonding electron pairs from ligands (Lewis bases) to form coordinate covalent bonds [1]. For instance, the hydration of Al3+ involves the metal ion accepting electron pairs from water molecules. Since the fundamental definition of a Lewis acid is its ability to accept an electron pair, Statement II provides the direct theoretical justification for Statement I [1]. Therefore, both statements are true, and Statement II is the correct explanation of Statement I.

Sources

1. [1] https://www.sciencedirect.com/topics/medicine-and-dentistry/lewis-acid