Why do molecular compounds have low melting points?

Question

I really need help answering this question. Does anybody know?

Answer 1

I believe that it has to do with the bonds between the molecules: those bonds must be broken in order for the compound to melt. When a compound is a solid, the molecules are pulled tightly together. But as a liquid, they are more separated. Compounds with low melting points have relatively weak bonds--like ionic bonds or hydrogen bonds. Those bonds can't hold the molecules together as tightly, making the compound able to melt at a lower temperature. Water, for instance, has hydrogen bonding. Obviously, it doesn't take a very high temp to melt it!

Hope that helps!

Answer 2

in molecular compounds particles are held by weak van der waal forces. that is the attractive forces are very weak n very less heat is need to change the state of such compounds. they are liquids for the same reason. the heat is taken in n so enough kinetic energy is acquired by the molecules, they vibrater n move faster breaking the weak forces quickly.
in case of ionic compounds, the attractive forces are very strong, therefore a large amount of heat is requierd to break them up n so they have high melting n boiling point.