Why does magnesium oxide have a very high melting point?
Answer and explanation
Correct answer: A. Strong electrostatic attractions between oppositely charged ions in a giant lattice need much energy to overcome
- Step 1: Magnesium oxide is a giant ionic lattice of and ions.
- Step 2: The attractions between and ions are strong, and a large amount of energy is needed to separate them.
Answer
Strong electrostatic attractions between oppositely charged ions in a giant lattice need much energy to overcome.
Why not the others: Strong covalent bonds between molecules of MgO need much energy to break: MgO is an ionic lattice, not made of covalent molecules. Weak forces between small molecules are easily overcome by heating: describes simple molecular substances with low melting points. Delocalised electrons hold the atoms together in a metallic structure: MgO is ionic and does not have a sea of delocalised electrons.
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