# Zwitterion --- **A zwitterion**, also called an "inner salt", is a [[molecule]] that contains an equal number of positively and negatively charged [[functional group|functional groups]]. The net [[charge]] of the entire molecule is, of course, zero. [[Amino acids]] are the best known examples of zwitterions. ![[zwitterion.png]] See how the proton transfer charges each functional group. %% line break below** ___