Why are intermolecular forces weaker than bonds?
Because it is the power of attraction or repulsion between atoms or molecules instead of sharing or giving/taking electrons.
Bonds that involve the exchange of electrons makes the "reacting" atoms more charged and hence tightly bound together due to the great amount of charge an electron has.
However, in non-reacting substances, the total charge of the molecules is almost zero. However, due to the orientation of different atoms in the molecule itself, a slight polarity can be observed.
This slight polarity will make the molecule itself slightly negative at one point and slightly positive at another. This will cause the molecules to attract at opposite charges and repel at similar charges.
Further reading is encouraged as this is a very vast subject.
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