# Why does increasing electronegativity difference result in decreasing density?

I've been collecting data and there's a very strong inverse relationship between electronegativity difference and density ($\pu{R^2}$ value of roughly 0.95 from my data). Is there any chemistry that could explain these results?

This doesn't make much sense to me because I would have thought increasing electronegativity difference would result in more polar bonds and thus more polar molecules, which would result in stronger inter-molecular forces and thus smaller volume (and hence more mass being packed into a smaller volume).

• The orbital size of the atoms with a negative dipole will increase relative to electronegativity , right? Since the electrons localize close to that point, I think the electron cloud would need to expand. – Bob May 29 '17 at 17:46
• What substances are you talking about? – DSVA May 29 '17 at 22:14