From a consideration of the Lewis structure of the thiocyanate ion, SCN–, in which carbon has a double bond with both the sulfur and nitrogen atoms, what are the formal charges on the sulfur, carbon, and nitrogen atoms?

1 Answer
Dec 23, 2017

Well, we got #6_S+4_C+5_N+1_"negative charge"=16# #"valence electrons"# to distribute over 3 centres...


As is typical we put the least electronegative atom in the middle...and we gets Lewis structures of....

#N-=C-S^(-)#, else, #""^(-)N=C=S#.

And thus the negative charge is conceived to lie on the nitrogen, or the sulfur atoms...the anion is LINEAR on the basis of VESPER. Because nitrogen is more electronegative than sulfur, we might anticipate that the resonance isomer on the right (as we face the page) is preferred on the resonance isomer on the left.