Writing Lewis Structure

Steps

1. Count the total number of valence electronsa. Add one for each negative chargeb. Subtract one for each positive charge

2. Write the skeletal structurea. Element with the least # of atoms or least

electronegative goes in the centerb. Connect bonded atoms with single bonds first

3. Complete an octet for all atoms remaininga. Exceptions: H, Al, B, Be

4. If there are not enough electrons, form double and triple bonds on the central atom as needed

Example 1: CF4

Example 2: NH3

Example 3: H2S

Example 4: NH4+

Example 5: PO43-

Example 6: CO2

Example 7: CO

Example 8: BCl4

RESONANCE

Draw the Lewis Structure for O3

Lewis Structure for O3

Example 9: NO3

−

Example 10: SO3