Chemical Bonding: Cl₃PO Lewis Structure

Drawing the Lewis Structure for Cl₃PO

Viewing Notes:

• The Lewis structure for Cl₃PO requires you to place Phosphorous (P) in the center of the structure since it is the most electronegative.
• You might think you've got the correct Lewis structure for Cl₃PO at first. Remember, Phosphorous is below Period 2 on teh Periodic Table and can hold more than 8 valence electrons.
• You'll want to calculate the formal charges on each atom to make sure you have the best Lewis structure for Cl₃PO.
• There are a total of 32 valence electrons for Cl₃PO.

This is the Cl3PO Lewis structure. For Cl3PO, we have a total of 32 valence electrons. Phosphorus is the least electronegative--we'll put that in the center--and then we have 3 Chlorines. Let's put them around the Phosphorus, and we'll put the Oxygen on top.

We have 32 valence electrons. We'll put 2 between each of the atoms to form chemical bonds. Then we'll go around the outside to complete the octets. We've used 8, 10, 12, and 32. At this point, we've used all 32 valence electrons and each of the atoms has an octet. The Phosphorus has an octet, Chlorines all have octets, and the Oxygen also has an octet.

So it looks like this is a pretty good structure for Cl3PO; however, because Phosphorus is below period 2, row 2 on the periodic table, we really need to check our charges to see if this is the most plausible Lewis structure for Cl3PO. For the Phosphorus, we have 5 valence eletctrons from the periodic table. Nonbonding: all of these electrons are bonding. All of these valence electrons are bonded, so we have 0. Minus bonding--we have 2, 4, 6, 8, and we'll divide that by 2. Five minus four gives us a plus one formal charge on the Phosphorus.

For the Chlorine, we have 7 from the periodic table. Minus nonbonding: each of the Chlorines is the same--they have 6 nonbonding. Minus bonding, we have 2 over 2. That equals 0. So all the Chlorines have a formal charge of 0.

Finally, we need to find the formal charge for the Oxygen. For Oxygen we have 6 valence electrons on the periodic table, minus our nonbonding--so these 6 right here, minus our bonding, these two right here, 2 over 2. That gives us a -1 formal charge for the Oxygen atom.

What we can do is take these two valence electrons on the Oxygen and form a double bond with the Phosphorus. We're still using the 32 valence electrons we had for the Cl3PO Lewis structure. But now if you recalculate the formal charges for each of the atoms, you'll find that they're all 0. This is what we want: the formal charges closer to zero mean a more plausible or likely Lewis structure. So we've used all 32 valence electrons, each of the atoms have octets, and our formal charges are 0.

That makes this the most plausible or likely Lewis structure for Cl3PO. This is Dr. B., and thanks for watching.