What is the Charge on SCN? And Why?

The Charge of SCN is 1-.

But the question is how can you find the charge on SCN (thiocyanate ion)?

Well there are 2 methods by which you can find the charge of SCN.

Lets dive right into these methods one by one.

You can also refer to the below video from which you will learn to find charge of any ion.

Method 1: By looking at what it is bonded to

The charge of SCN (thiocyanate ion) can be found out by looking at what it is bonded to.

So let’s take some examples of compounds that contain SCN; like NaSCN, KSCN, etc.

Example 1: NaSCN
In NaSCN, the SCN is bonded to Sodium (Na).
You know that the ionic charge of Na is 1+.
So you can easily say that the charge of SCN should be 1-, then only it will get canceled out.
Hence the charge of SCN in NaSCN is 1-.

Example 2: KSCN
In KSCN, the SCN is bonded to Potassium (K).
And again, you know that the ionic charge of K is 1+.
So here also you can easily say that the charge of SCN should be 1-, then only it will get canceled out.
Hence the charge of SCN in KSCN is 1-.

As seen from the above examples,
The charge of SCN is 1-.

In this way, you can easily find the charge of SCN by looking at what it is bonded to.

Method 2: By calculating the formal charge using lewis structure

In order to calculate the formal charge on SCN (thiocyanate ion), you should know the Lewis dot structure of SCN (thiocyanate ion).

Here is the lewis structure of SCN.

Now using the above lewis structure of SCN, you have to find the formal charge on each atom that is present in the SCN molecule.

For calculating the formal charge, you need to remember this formula;

Formal charge = Valence electrons – Nonbonding electrons – (Bonding electrons)/2

You can see the bonding and nonbonding electrons of SCN from the image given below.

So now let’s calculate the formal charge on each individual atom present in SCN.

Formal charge on Sulfur atom:
Valence electrons = 6 (as it is in group 16 on periodic table) ^[1]
Nonbonding electrons = 4
Bonding electrons = 4

So according to the formula of formal charge, you will get;

Formal charge on Sulfur = Valence electrons – Nonbonding electrons – (Bonding electrons)/2 = 6 – 4 – (4/2) = 0

So the formal charge on sulfur atom is 0.

Formal charge on Carbon atom:
Valence electron = 4 (as it is in group 14 on periodic table) ^[2]
Nonbonding electrons = 0
Bonding electrons = 8

So according to the formula of formal charge, you will get;

Formal charge on Carbon = Valence electrons – Nonbonding electrons – (Bonding electrons)/2 = 4 – 0 – (8/2) = 0

So the formal charge on carbon atom is 0.

Formal charge on Nitrogen atom:
Valence electron = 5 (as it is in group 15 on periodic table) ^[3]
Nonbonding electrons = 4
Bonding electrons = 4

So according to the formula of formal charge, you will get;

Formal charge on Nitrogen = Valence electrons – Nonbonding electrons – (Bonding electrons)/2 = 5 – 4 – (4/2) = 1-

So the formal charge on nitrogen atom is 1-.

Now let’s put all these charges on the lewis dot structure of SCN.

So there is overall 1- charge left on the entire molecule.

This indicates that the SCN (thiocyanate ion) has 1- charge.

I hope you have understood the above calculations of SCN (thiocyanate ion). But for your tests, you don’t need to remember the entire calculations. You should just try to remember that SCN has 1- charge.

Check out some other related topics for your practice.

Related topics:
Charge on H3PO4
Charge on HSO4 (Hydrogen Sulfate ion)
Charge on Methane (CH4)
Charge of Antimony (Sb)
Charge of Molybdenum (Mo)