Ionic compounds

(1) They conduct electricity when in molten state because when they are dissolved in water, the ions of the compound can move about. The moving ions carry the electric current. In the solid state, the ions cannot move, so the current cannot flow.

(2) They have high melting and boiling points because the ionic bonds between the ions are very strong. A very large amount of heat is needed to break these strong bonds up.
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Covalent compounds

(1) The forces between the molecules of the covalent compounds are weak, hence these forces are easily broken. That is why they have low melting and boiling points.

(2) They do not conduct electricity in any state. This is because they do not contain ions.
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I'm revising my chemistry now -o-
Currently on the MOLES topic.
k i'm kind of distracted by the com. But still, I'm not gonna shut it down cos' I'll on it back one lor. HEHE. I know i'm cute.