Explain why some larger nonpolar molecular solids are solid at room temperature:
Since non-polar substances only have dispersion forces, you might not expect solid non-polar molecules to exist at room temperature. Recall that dispersion forces are very week compared to other types of IMFs. However, larger and heavier atoms and molecules exhibit stronger dispersion forces than smaller and lighter ones. In a larger atom or molecule, the valence electrons are, on average, farther from the nuclei than in a smaller atom or molecule. They are less tightly held and can more easily form temporary dipoles. The dispersion forces in larger molecules are quite significant, which results in some larger non-polar molecular solids at room temperature, especially hydrocarbons.