PCl3 is a covalent (polar covalent) compound because when one nonmetal combines with another nonmetal, it usually forms a covalent compound. Here, P is a nonmetal and Cl is also a nonmetal. So when they combine, it forms a covalent compound.
Well, now you have got to know that PCl3 is a covalent compound, but let me explain the in-depth reason why PCl3 is a covalent compound.
If you are a visual learner like me, then here is a short one minute video for you.
Why is PCl3 a Covalent compound?
As mentioned above, you can simply remember that when the nonmetal combines with another nonmetal, the bond between them is a covalent bond.
Here in PCl3, the P atom is a nonmetal and the Cl atom is also a nonmetal.
Hence the bond between them is a covalent bond.
How does the covalent bond form between P and Cl?
In PCl3, there are two atoms;
P and Cl.
About Phosphorus (P):
Phosphorus atom have 15 electrons.
The electrons arrangement in Phosphorus (P) is 2, 8, 5.
So the outermost orbit of Phosphorus atom has 5 electrons.
Now in order to achieve a stable octet, the Phosphorus atom needs 3 more electrons.
Hence during the chemical reaction, the Phosphorus atom will gain 3 electrons from the combining atom to form a stable octet.
About Chlorine (Cl):
Chlorine atom have 17 electrons.
The electrons arrangement in Chlorine (Cl) is 2, 8, 7.
So the outermost orbit of Chlorine atom has 7 electrons.
Now in order to achieve a stable octet, the Chlorine atom needs 1 more electron.
Hence during the chemical reaction, the Chlorine atom will gain 1 electron from the combining atom to form a stable octet.
What happens when P and Cl combine?
When P and Cl combine with each other, the Phosphorus atom and Chlorine atoms mutually share their 1-1 electrons with each other.
Because of this the phosphorus atom will have 8 electrons in its outermost orbit and similarly the chlorine atom will also have 8 electrons in its outermost orbit.
As a result, the phosphorus atom as well as chlorine atom will have a stable octet.
And finally, as the bond formed between the phosphorus and chlorine is due to the mutual sharing of electrons, it is considered a covalent bond.
Thus, PCl3 is a covalent compound.
Is PCl3 polar covalent or nonpolar covalent?
In order to know whether PCl3 is a polar covalent molecule or nonpolar covalent molecule, we have to check the electronegativity difference of the combining atoms.
If the electronegativity difference (ΔEN) is less than 0.4, then the bond is nonpolar covalent bond.
Now the electronegativity of Phosphorus and Chlorine are mentioned below. (You can see the electronegativity of all the elements from this electronegativity chart).
- Electronegativity of Phosphorus (P) = 2.19
- Electronegativity of Chlorine (Cl) = 3.16
So for PCl3, the electronegativity difference (ΔEN) = 3.16 – 2.19 = 0.97
This value lies between 0.4 to 1.7, which indicates that the bond between Phosphorus (P) and Chlorine (Cl) is polar covalent bond.
But the PCl3 molecule has 1 lone pair which results in an asymmetric shape of the entire PCl3 molecule.
Because of this asymmetric shape there are positive and negative poles of charges on the overall molecule of PCl3.
Hence, PCl3 is a polar covalent molecule.
I hope you have understood the reason why PCl3 is a polar covalent compound.
Check out other compounds to see whether they are ionic or covalent;
Is SF6 (Sulfur hexafluoride) Ionic or Covalent?
Is SO3 Ionic or Covalent?
Is CaF2 Ionic or Covalent?
Is K2O Ionic or Covalent?
Is KBr Ionic or Covalent?
Jay is an educator and has helped more than 100,000 students in their studies by providing simple and easy explanations on different science-related topics. With a desire to make learning accessible for everyone, he founded Knords Learning, an online learning platform that provides students with easily understandable explanations.
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