Question

What are the formal charges on the sulfur (s), carbon (c), and nitrogen (n) atoms, respectively, in the resonance structure that contributes most to the stability of the thiocyanate ion, scn−?

Answer 1

In the preferred resonance structure of thiocyanate ion, the formal charges are -1 for sulfur, 0 for carbon, and 0 for nitrogen, which aligns with the stability guidelines.

Step-by-step explanation:

The thiocyanate ion (SCN−) can be arranged in various ways, but the one that contributes most to its stability is the NCS arrangement. This is due to stability guidelines suggesting that structures with the lowest number of nonzero formal charges and negative charges on the more electronegative atoms are more stable. In the case of the thiocyanate ion, sulfur (S) will have a formal charge of -1, carbon (C) will have a formal charge of 0, and nitrogen (N) will also have a formal charge of 0. When considering the electronegativity of each atom, it makes sense to place the negative charge on sulfur, as it is more electronegative than carbon but less than nitrogen. Therefore, the preferred resonance structure is [:N=C=S:]− which places the negative charge on sulfur, has carbon in the middle, and nitrogen on one end with no formal charges.

Answer 2

0, 0, -1

Step-by-step explanation:

There are three resonance contributors to the resonance hybrid of the SCN⁻ ion.

The one on the right is the least stable because it has the greatest separation of charge.

The remaining structures each have one negative charge.

The structure in the middle is the most stable and most important contributor because it has the negative charge on the most electronegative atom — N.

The formal charges on S, C, and N are 0, 0, and -1.