Bond energies can be reliably used to calculate heats of reaction. Mathematical or mental constructs such as electron clouds represent something solid. When solid models are used to illustrate atomic scale events, it is possible to produce this misconception among students. It is quite natural for students to develop this picture since both solid models and pictures resemble solids. Caution students about taking an overly-literal view of such models.
Intermolecular bonds are the same as intramolecular bonds.
Yet temperatures of several thousand degrees Celsius do not cause appreciable decomposition of N2 molecules because the nitrogen atoms in the N2 molecule are bonded with a triple covalent intramolecular bond. This is a strong, primary chemical bond whereas van der Waals forces are quite weak intermolecular forces that require relatively little energy to overcome. See the discussion above for Item 4.