There was a question asking why magnesium metal has a higher melting point than sodium.
In the answer, they said:
- Magnesium has more delocalised electrons.
- Magnesium ions have a greater positive charge.
- Magnesium has a greater electrostatic attraction between ions and delocalised electrons.
However, in the mark scheme in the additional guidance, it also said the mark couldn't be given if you said:
Magnesium ions have a great nuclear charge rather than greater positive charge.
I was confused as to what the difference is.