Question

why metals have high melting and boiling point

Answer 1

Metals have high melting and boiling points because in metals there is a very strong intermolecular force of attraction and it needs a lot of energy to melt or to boil

Answer 2

The bonding within metals is called metallic bonding, where there is a sea of mobile delocalized electrons. There are very strong forces between the electrons which are hard to overcome and so it requires much more energy to break.