The document provides instructions for drawing the Lewis structure of carbon monoxide (CO). It explains that carbon contributes 4 valence electrons and oxygen contributes 6, for a total of 10. A carbon-oxygen single bond is drawn by pairing 2 electrons between them. However, carbon then only has 6 electrons and needs 8 to complete its octet. Therefore, oxygen must donate its remaining 2 electrons to carbon to form a triple bond, completing the octet for both atoms.

1. How to draw the Lewis structure
of carbon monoxide, CO
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2. Steps to draw the Lewis structure
1. Find the number of valence electrons for
each of the atoms in the molecule.
The number of valence electrons is usually the
same as the group number where the element
is located.

3. The number of valence electrons for carbon is 4 (group 4)

4. The number of valence electrons for oxygen is 6 (group 6)

5. 2. Count the total number of valence electrons
in the molecule:
Sum the valence electrons from each atom in
the molecule

6. For CO
• Total valence e. from C: 4
4 e. x 1 C = 4
• Total valence e. from O: 6
6 e. x 1O = 6
Total valence e. in the molecule: 4 + 6 = 10

7. 3. Use the octet rule to figure how many octet
electrons the atoms should have:
Most atoms need 8 electrons to complete their
valence shield
Hydrogen is an exception and needs only 2

8. For CO
• Carbon should have 8 valence electrons
• Oxygen should have 8 valence electrons

9. 4. Draw an initial sketch of the molecule by
placing the symbol of each atom in a diagram
For carbon monoxide, CO
O C

10. 5. Place the valence electrons of each
atom around them, starting from the
outer atoms

11. For CO
• Oxygen has 6 valence electrons:

12. For CO
• Carbon has 4 valence electrons:

13. 6. Each bond in a molecule is made up from
two electrons.
Each atom in the molecule need to be bonded
together to its nearest atom.

14. For CO

15. Single bond

16. Count the number of electrons each atom has after
forming a single bond:
Oxygen atom has 7 electrons, it needs 8

17. Count the number of electrons each atom has after
forming a single bond:
Carbon atom has 5 electrons, it needs 8

18. To complete the octet we would need to pair
more couple of electrons for each atom

19. Pair another couple of electrons for each atom:

20. Now count the number of electrons around
each atom:
Oxygen has 8 electrons

21. Now count the number of electrons around
each atom:
But carbon only 6!

22. In order for carbon to have 8 electrons, oxygen
must donate 2 electrons to participate in a
bond:

23. In order for carbon to have 8 electrons, oxygen
must donate 2 electrons to participate in a
single bond:

24. Now carbon is also surrounded by 8 electrons:

25. Now we just need to change the dots for lines to
represent a triple bond:

26. Practice writing the Lewis structure of any other
molecule!
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