text: how many lone-pairs of electrons are on the central atom? i have the following compounds:  so3 molecule, icl3 molecule, and n3- ion and i need to determine how many lone-pairs of electrons are on the central atom of each.  my answers:  s ==> 2 ; i ==> 2 ; n ==> 2  am i right? no:  s --> 0 (hint: there is one s=o bond);  the other two are correct.