Draw the Lewis Dot Structure for POCl 3 .

So here it says, draw the Lewis dot structure for p o c l three. So here, phosphorus is in group 5 a, oxygen's in group 6 a, chlorine is in group 7 a, and there's 3 of them. So our total number of valence electrons is 5 plus 6 plus 21, so that comes out to 32 total valence electrons. We place the least electronegative element in center which is phosphorus. It is forming single bonds to the to the chlorine initially and the oxygen. Then we make sure that the surrounding elements are following the octet rule. So seeing that we've used all 32 of our electrons. Right? Now this would like it is the best representation, but we should check. Formal charge, oxygen is in group 6 a, so it has 6 minus the number of bonds it's making, which is 1, plus 6 individual nonbonding electrons, makes it negative 1. Phosphorus is in group 5 a, we see it making 4 bonds and has no nonbonding electrons. And then the chlorines are all in group 7 a. Just focus on 1 of the chlorines, making one bond and it has 6 electrons not bonded. When I add them all up together, yes, it gives me a charge of 0, and the molecule has a charge of 0. But this would not be the best representation. Again, we're dealing with weird molecules that have exceptions involved. So here, another way I could depict this is I could instead decide to make a double bond between the oxygen and the phosphorus. Remember, halogens like chlorine, when they're a surrounding element, they can only make single bonds. So I could not make a double bond with any of the chlorines. Now if I were to figure out the new formal charges, first of all the chlorine stayed the same so they're still 0. Phosphorus here would be 5 minus the 5 bonds it's making plus 0, which is 0. And oxygen would be group 6 a. We see it making 2 bonds and has 4 electron 4 electrons not bonding, so that's also 0. Here, this would be the better way of showing this molecule, because it gives us the least number of formal charges, meaning it gives us the most 0 formal charges. Here, although this is okay, it is not the best depiction of this molecule. This would be the best depiction. And remember, this is possible because phosphorus can expand its octet and have more than 8 total octet electrons around itself.

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11. Bonding & Molecular Structure

Lewis Dot Structures: Exceptions

General Chemistry

11. Bonding & Molecular Structure

Lewis Dot Structures: Exceptions

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Multiple Choice

Draw the Lewis Dot Structure for POCl₃.

Lewis Dot Structure for POCl3 showing bonds and lone pairs.

Alternative Lewis Dot Structure for POCl3 with different bond representation.

Another variation of the Lewis Dot Structure for POCl3.

Final representation of the Lewis Dot Structure for POCl3.

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Verified step by step guidance

Identify the central atom in the molecule POCl₃. Phosphorus (P) is typically the central atom because it can form multiple bonds and has a lower electronegativity compared to oxygen (O) and chlorine (Cl).

Determine the total number of valence electrons available for the molecule. Phosphorus has 5 valence electrons, oxygen has 6, and each chlorine has 7. Therefore, the total number of valence electrons is: 5 + 6 + (3 × 7) = 32 valence electrons.

Arrange the atoms around the central phosphorus atom. Place oxygen and the three chlorine atoms around phosphorus. Connect each atom to phosphorus with a single bond initially.

Distribute the remaining valence electrons to satisfy the octet rule for each atom. Start by completing the octet for the outer atoms (oxygen and chlorine) and then adjust the central atom if necessary. Oxygen typically forms a double bond with phosphorus to satisfy its octet.

Check the formal charges to ensure the most stable structure. The formal charge is calculated using the formula: Formal Charge = Valence Electrons - Nonbonding Electrons - (Bonding Electrons / 2). Adjust the bonds if necessary to minimize formal charges across the molecule.