. Answer the following question: a. Draw a Lewis structure for the compound phosphoryl chloride (POCl
) b. Mention the type of bond in the compound (POCl
) c. Is the compound (POCl
) Polar or Nonpolar
The Correct Answer and Explanation is:
a. Lewis Structure of Phosphoryl Chloride (POCl₃):
- Count the Valence Electrons:
- Phosphorus (P): 5 valence electrons.
- Oxygen (O): 6 valence electrons.
- Chlorine (Cl): 7 valence electrons, and there are three chlorine atoms.
- Arrangement:
- Phosphorus is the central atom since it is less electronegative than oxygen or chlorine.
- Oxygen is bonded to phosphorus, and each chlorine atom is bonded to phosphorus.
- Drawing the Bonds:
- P will form a double bond with O and single bonds with each Cl atom.
- Each chlorine will have three lone pairs of electrons.
- Final Structure:
- The central phosphorus atom (P) is double-bonded to the oxygen atom (O) and single-bonded to three chlorine (Cl) atoms.
- Each chlorine atom will have three lone pairs of electrons, and oxygen will have two lone pairs.
Cl Cl | | Cl–P=O | Cl
b. Type of Bond in POCl₃:
- The bonds in POCl₃ are polar covalent bonds.
- Phosphorus and oxygen have a large electronegativity difference, so the bond between them is highly polar.
- The P–Cl bonds are also polar, as chlorine is more electronegative than phosphorus. However, the difference is not as significant as between P and O.
c. Is POCl₃ Polar or Nonpolar?
- POCl₃ is a polar molecule.
- Despite the individual P–Cl and P=O bonds being polar, the molecule as a whole is polar due to its asymmetric shape. Phosphoryl chloride adopts a trigonal pyramidal shape with phosphorus at the center, oxygen at the apex, and three chlorine atoms forming the base. This asymmetry leads to a net dipole moment, which makes POCl₃ polar.
In conclusion:
- POCl₃ is a polar compound with polar covalent bonds.
