CN- (Cyanide ion) is a POLAR ion.
But why?
And how can you say that CN- is a polar ion?
Want to know the reason?
Let’s dive into it!
CN- (Cyanide ion) is a POLAR ion because any two bonding atoms whose electronegativity difference is between 0.4 to 2.0 forms a polar bond.
Here in CN- ion, the electronegativity difference of Carbon atom (C = 2.55) and Nitrogen atom (N = 3.04) is 0.49 (i.e 3.04 – 2.55 = 0.49). This value (0.49) is between 0.4 and 2.0, hence the CN- ion is a polar ion.
Didn’t understand what is written above?
Let me explain this in a short and simple way (with 3D images).
Why is CN- ion a Polar ion? (Explained!)
CN- ion is a polar ion because it has a partial positive charge (ẟ+) on the Carbon atom and partial negative charge (ẟ-) on the Nitrogen atom.
In short, the CN- ion forms a pole of positive charge and negative charge on it. Hence CN- ion is a polar ion.
But wait, let me give you some detailed information about the polarity of CN- ion.
The chemical bonds can be either nonpolar, polar or ionic depending on the difference of the electronegativity values (ΔEN) between the two atoms.
Have a look at the above image.
- If the electronegativity difference (ΔEN) is less than 0.4, then the bond is nonpolar covalent bond.
- If the electronegativity difference (ΔEN) is between 0.4 to 1.7, then the bond is polar covalent bond.
- If the electronegativity difference (ΔEN) is greater than 1.7, then the bond is an ionic bond. [1] [2] [3] [4]
Now let’s come to the example of CN- ion.
You can see the electronegativity values of Carbon (C) and Nitrogen (N) atoms from the periodic table given below.
From the above image;
So for CN- ion, the electronegativity difference (ΔEN) = 3.04 – 2.55 = 0.49
This value lies between 0.4 to 1.7, which indicates that the bond between Carbon (C) and Nitrogen (N) is polar covalent bond.
Hence, CN- ion is a polar ion.
How CN- ion becomes a Polar ion?
In a CN- ion, there is one carbon atom (C) and one nitrogen atom (N). Both these atoms are covalently bonded with each other by sharing three electron pairs between them.
If we compare the electronegativity of carbon and nitrogen, then nitrogen is more electronegative than carbon.
This means that the nitrogen atom has more tendency to attract the shared electron pair towards itself.
As the electron pair remains attracted towards the nitrogen atom, the partial negative charge (ẟ-) appears on the Nitrogen atom (N) and partial positive charge (ẟ+) appears on the Carbon atom (C).
In this way the partial positive and partial negative charges are generated on the CN- ion and hence CN- becomes a polar ion.
I hope you have understood the reason behind the polarity of CN- ion.
See the polarity of other molecules to make your concepts clear:
Is N2H4 Polar or Nonpolar?
Is SeCl2 Polar or Nonpolar?
Is BeI2 Polar or Nonpolar?
Is TeF4 Polar or Nonpolar?
Is AlBr3 Polar or Nonpolar?
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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