Question

1. write lewis structures for the following. show all resonance structures where applicable. for c and d, the central atom is carbon: 4

a) no2-
b) no3-
c) ocn-
d) scn-

Explanation:

Lewis structures show valence electrons, bonds, and lone pairs. Resonance structures differ by double bond placement (same atom connectivity). Central atoms: N for a/b, C for c/d.

Answer:

a) $\text{NO}_2^-$:
Central N bonded to two O (one double, one single); N has 1 lone pair, single-bonded O has 3 lone pairs, double-bonded O has 2 lone pairs. 2 resonance structures (double bond alternates between O atoms).

b) $\text{NO}_3^-$:
Central N bonded to three O (one double, two single); N has 0 lone pairs, single-bonded O have 3 lone pairs each, double-bonded O has 2 lone pairs. 3 resonance structures (double bond alternates among O atoms).

c) $\text{OCN}^-$:
Central C bonded to O (double) and N (triple); O has 2 lone pairs, N has 1 lone pair. Resonance structures: C=O and C≡N ↔ C≡O and C=N⁻.

d) $\text{SCN}^-$:
Central C bonded to S (double) and N (triple); S has 2 lone pairs, N has 1 lone pair. Resonance structures: C=S and C≡N ↔ C≡S and C=N⁻.