To draw a reasonable resonance structure for the OCN ion, follow these steps:
- Identify the Skeletal Structure: The given skeletal structure is O-C-N.
- Determine the Total Number of Valence Electrons: Oxygen has 6, Carbon has 4, and Nitrogen has 5. Adding one extra electron for the negative charge, the total is 16 valence electrons.
- Draw the Initial Structure: Place a single bond between O and C, and a triple bond between C and N. This uses 8 electrons (2 for the single bond and 6 for the triple bond).
- Add Lone Pairs: Place lone pairs on the atoms to complete their octets. Oxygen will have 2 lone pairs, Carbon will have no lone pairs, and Nitrogen will have 1 lone pair. This uses 10 more electrons.
- Check Formal Charges: Calculate the formal charges for each atom. Oxygen has a formal charge of -1, Carbon has a formal charge of 0, and Nitrogen has a formal charge of 0.
- Draw the Resonance Structure: Move a lone pair from Oxygen to form a double bond between O and C. This changes the formal charges: Oxygen now has a formal charge of 0, Carbon has a formal charge of +1, and Nitrogen has a formal charge of -1.
Here is the resonance structure:
O=C=N
This structure is one of the possible resonance forms for the OCN ion, showing the distribution of electrons and formal charges.