Question

draw a resonance structure for the thiocyanate ion, scn⁻, where each atom has an octet and the most electronegative atom has a formal charge equal to - 2. be sure to include all lone pair electrons and nonzero formal charges. click and drag to start drawing a structure.

Explanation:

Step1: Determine valence electrons

S has 6, C has 4, N has 5 and there is 1 extra electron due to - 1 charge. Total = 6 + 4+5 + 1=16 valence electrons.

Step2: Identify most electronegative atom

N is the most electronegative atom among S, C and N.

Step3: Start constructing structure

Place C in the middle as it can form multiple bonds. Connect S - C - N.

Step4: Distribute electrons to get octets

First, form single - bonds S - C and C - N. Then add lone - pairs and multiple bonds to satisfy octets and formal charge requirements. A possible resonance structure is $S\equiv C-\ddot{N}:^{2 - }$. S has a triple - bond with C (6 electrons around S), C has 8 electrons (4 from bonds), and N has 8 electrons (2 from bond and 6 as lone - pairs) with a formal charge of - 2.

Answer:

$S\equiv C-\ddot{N}:^{2 - }$ (with lone - pairs and formal charge shown as above)