Answer :
Final answer:
Magnesium has a higher melting point compared to sodium because it has stronger metallic bonds due to having more valence electrons that contribute to a greater extent of metallic bonding. This results in higher lattice energies and stronger attractions between ions, especially noted in compounds such as magnesium oxide compared to sodium chloride. So correct answer is option d) Magnesium has stronger metallic bonds.
Explanation:
The question why does magnesium have a higher melting point compared to sodium involves understanding metallic bonds and the impact of valence electrons on the strength of these bonds. Magnesium has stronger metallic bonds.' This is because magnesium has more valence electrons (two, compared to sodium's one) that can participate in metallic bonding. In metallic bonds, free electrons move between atoms, strengthening the bond between them. This phenomenon explains why magnesium, with its two valence electrons contributing to the sea of electrons, has stronger metallic bonds and hence a higher melting point compared to sodium, which contributes only one electron. Additionally, stronger metallic bonds in magnesium contribute to higher lattice energies, reflecting in significantly higher melting points. For instance, magnesium oxide (MgO) has a much higher melting point compared to sodium chloride (NaCl) because in MgO, 2+ ions are attracting 2- ions, creating stronger attractions due to the higher charges of ions compared to the 1+ and 1- ion attraction in NaCl.
