1. Writing Lewis Structures

2. Steps Count the total number of valence electrons
Add one for each negative charge
Subtract one for each positive charge
Write the skeletal structure
Element with the least # of atoms or least electronegative goes in the center
Connect bonded atoms with single bonds first

3. Complete an octet for all atoms remaining (start with most electronegative atom first)
Exceptions: H, Al, B, Be
If there are not enough electrons, form double and triple bonds with the central atom as needed

4. Example 1: CF4

5. Example 2: NH3

6. Example 3: CH2O

7. Example 4: H3O+

8. Example 5: CO2

9. Example 6: HCN

10. Example 7: BCl3

11. Example 8: OCN-

12. Example 8: CO32-

13. Example 10: O3