1. V. Lewis Dot Diagrams for Double & Triple Bonds + Polyatomic Ions

2. Recall…L.D.D. Steps Total # of valence electrons
Total # of valence electrons needed to fulfill octet rule
(Step 2 – Step 1)/2
Choose central atom (least electronegative)
Connect atoms to central atom (use step 3)
Place remaining valence electrons around outside atoms. Left over valence electrons go on central atom

3. A. Double/Triple Bonds
Single covalent bond = 1 shared pair of electrons (2 total)
Double covalent bond = 2 shared pairs of electrons (4 total)
Triple covalent bond = 3 shared pairs of electrons (6 total)

4. Example #1: CO2 Total # of valence electrons
Total # of valence electrons needed to fulfill octet rule
(Step 2 – Step 1)/2
Choose central atom
Connect atoms to central atom (use step 3)
Place remaining valence electrons around outside atoms. Left over valence electrons go on central atom

5. Example #2: N2 Total # of valence electrons
Total # of valence electrons needed to fulfill octet rule
(Step 2 – Step 1)/2
Choose central atom
Connect atoms to central atom (use step 3)
Place remaining valence electrons around outside atoms. Left over valence electrons go on central atom

6. Example #3: HCCH Total # of valence electrons
Total # of valence electrons needed to fulfill octet rule
(Step 2 – Step 1)/2
Choose central atom
Connect atoms to central atom (use step 3)
Place remaining valence electrons around outside atoms. Left over valence electrons go on central atom

7. Polyatomic Example #1: SO42–
Total # of valence electrons
Total # of valence electrons needed to fulfill octet rule
(Step 2 – Step 1)/2
Choose central atom
Connect atoms to central atom (use step 3)
Place remaining valence electrons around outside atoms. Left over valence electrons go on central atom

8. Polyatomic Example #2: NO–
Total # of valence electrons
Total # of valence electrons needed to fulfill octet rule
(Step 2 – Step 1)/2
Choose central atom
Connect atoms to central atom (use step 3)
Place remaining valence electrons around outside atoms. Left over valence electrons go on central atom