Writing Lewis Structures

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

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

Example 1: CF4

Example 2: NH3

Example 3: CH2O

Example 4: H3O+

Example 5: CO2

Example 6: HCN

Example 7: BCl3

Example 8: OCN-

Example 8: CO32-

Example 10: O3