Question

Why covalently bonded molecules have the strong bonds within the molecules but their intermolecular forces of attraction are weak Why?

Answer 1

Dear Student,
The bond formed within the molecule is quite strong because it involves the sharing of electrons. Hence this bond is difficult to break and requires energy.
while the intermolecular forces of attraction are weak in nature because these are just the forces that act between the molecules (these may be dipole-dipole or ion -dipole interactions )
The nucleus has a hold of attraction on the bonded electrons and keeps the bond formed strong while in intermolecular forces the nucleus does not have such a strong attractive force upon the electrons therefore they are weaker.
To understand the concept of strength of intramolecular and intermolecular forces .think of the relations between your own family and your neighbourhood family . you hold a close relation and love affection with your family .This represents a covalent bond while the neighbours may be very polite and humble you are attached to them but not as strongly as your family , this will be a kind of intermolecular force of attraction.
I hope this explains you well!
Regards!