In my notes it says that it's because of the delocalised electrons, but what does that have to do with it when the nuclei of metals in metallic bonding are charged '2+'?
sodium has one delocalised electron per atom and atoms have a +1 charge magnesium has 2 and +2 and aluminium has 3 and +3 the greater charge and greater number of electrons means that the atoms are held in place more securly and so they do not melt as easily
