CHEMISTRY COMMUNITY

For problem 6.21 in the homework, it says that the given molecule can only accept two protons. My first guess would be that it could accept 6 because of the two lone pairs on each oxygen and then the one lone pair on the two nitrogens. Why can't the oxygens accept protons?

Since oxygen is more electronegative than nitrogen, it is less likely to share its electrons with a proton. Thus, the nitrogens are able to accept protons while the oxygens are not.