Thiocyanate (SCN) is an atom or molecule with a net electrical charge. It’s also called rhodanide. It is one of the best products of cyanide and glycosinolates.
Cyanide is a colorless gas and exists in various forms, and glycosinolates are the thioglycosides found in different vegetables and brassica families, including cabbage, broccoli, eggplant, etc.
The SCN ions form salts, potassium thiocyanate, and sodium thiocyanate.
Are you wondering is SCN polar or nonpolar? Don’t worry because this article will help you to clarify all your confusion about SCN polarity.
The formula of thiocyanate is SCN.
The SCN ions have one sulfur, carbon, and a nitrogen atom.
Is SCN Polar Or Nonpolar
The SCN is a polar molecule due to the difference in electronegativity between sulfur, carbon, and nitrogen. The electronegativity difference between sulfur(2.58), carbon(2.55), and nitrogen(3.04) is less similar. The partial negative charge is found closer to the nitrogen atom that pulls the electron from carbon and sulfur.
The SCN is a polar molecule because, in SCN, the nitrogen and sulfur atoms attract the electrons from the carbon atom, which results in a negative charge on nitrogen and sulfur, and a partial positive charge on the carbon atom; therefore, SCN is polar.
Simple is that SCN is a polar molecule, above are the two reasons why SCN is polar.
SCN Molecular Geometry
The molecular geometry of thiocyanate ion( SCN-) is linear. According to VSEPR theory, we can determine the shape or molecular geometry from the electron’s pair number present in the central atom.
As you can see in the above picture, the thiocyanate ion (SCN-) has three atoms, sulfur, carbon, and nitrogen, which bonded with each other. The carbon is in the center, and nitrogen and sulfur surrounding the carbon atom.
The number of a bonded atom is two, and there are no lone pairs, which resulting in SCN has linear molecular geometry.
In SCN, all three atoms are bonded, which produces an ion with a linear shape.
SCN Lewis Structure
The Lewis structure of SCN is challenging because it has different structures from other chemical compounds.
You may not understand the below points before watching the video. That is why I will recommend watching the video first before reading the below instructions.
To draw the SCN Lewis structure, follow the below instructions.
- The above structure is the resonance structure. Each of these uses all 16 valence electrons.
- The formal charges for each one add up to a negative one, which means we have negative 1 up at the above of (SCN-).
- Now look at the formal charges for each one and see what’s going on and which one will be the best Lewis structure for SCN-.
- The sulfur is number 6 in the periodic table, which has 6 valence electrons, and these all are nonbonding.
- The two are involved in a chemical bond, so we will divide that by 2, which resulting sulfur has a negative one charge.
- The carbon and nitrogen both have formal charges of zero.
- In the next Lewis structure, the sulfur and the carbon both have zero formal charges.
- The nitrogen is number 5 in the periodic table, with 5 valence electrons and four nonbonding valence electrons resulting in a negative one charge.
- At last, both structures will become mostly identical, but you need to decide which is going to be mostly molecule for the SCN- ion to exist.
Watch the below video to select which one is going to be the best Lewis structure for SCN.
The SCN- has sp hybridization. In SCN, carbon is the least electronegativity and the highest valence electrons between S and N; therefore, place the carbon atom in the central.
The atom that has the highest valence electrons and least electronegativity is generally the central atom.
In SCN, carbon has an sp hybridization.
What Type Of Ligand Is SCN
The SCN has an Ambidentate ligand because thiocyanate (SCN) shares a negative charge equally between sulfur and nitrogen. Ambidentate ligands bond to the central atom in two places due to more than one donor atom.
The SCN is a weak field ligand, and NCS is a strong field ligand.
The ligand of SCN is Ambidentate.
Why Is The Charge Of SCN -1
In SCN, the oxidation state of sulfur, carbon, and nitrogen is ( sulfur=02 to +6, carbon= -4 to +4, and nitrogen= -3 to +5), So if you check the combination of all of these atoms oxidation state, there are lots of combination in oxidation state which resulting -1 charge.
The addition electron in the SCN- ion is one, and there are two possibilities to place the formal charge of -1.
You can place it on sulfur or nitrogen, like this.
S=C=N(-) <−> (-)S−C≡N
Keep in mind that if you want to determine an overall arrangement of atoms in a molecule, then the formal charge is more useful for it, but it is not too useful for the arrangement of electrons.
Simple is that SCN has a -1 charge due to lots of oxidation state.
Sources Of Thiocyanate (SCN)
- It is found in many plants, such as broccoli, cabbage, and turnips.
- Cyanide is found in the smoke of the cigarette.
- It is also found in the blood of the human.
Above are the major sources of Thiocyanate.
Properties Of Thiocyanate (SCN)
- The chemical formula of thiocyanate is SCN−.
- Its molar mass is 58.08 g·mol−1.
- It is soluble in water.
- It is a less toxic molecule due to its cyanide and thiosulfate association.
- It’s acidic in nature.
Above are the properties of SCN.
Uses Of Thiocyanate (SCN)
- Thiocyanate is used in the treatment of hypertension.
- It is also found in the urine samples.
- SCN is used for producing hypo thiocyanic acid.
- It is used for determining Fe(III), W, Mo, Re, Nb, U, Co, and Ti.
- Thiocyanate ion is widely used as one of the important spectrophotometric reagents.
Above are the few uses of Thiocyanate (SCN).
What Color is SCN?
SCN is colorless, and Fe3+ is yellow, so the [FeSCN]2+ color is red such as blood. Sometimes changes occur in color. It maybe changes to lighter red or darker red.
Is SCN soluble?
Yes, mostly all salts of SCN are soluble except this Cu+, Ag +, Hg22+ and Pb2+. PbCl2 is soluble in hot water, and HgI2 is insoluble in hot water.
Why is iron thiocyanate red?
The iron thiocyanate is red because of the below reaction.
Fe3+ + [SCN]- ===> [Fe (SCN)]2+
The reaction reaches the equilibrium stage, and then the direct reaction (from left to right) adds a small amount of acid.
That was all about is SCN polar or nonpolar. I hope it’s now clear to you that SCN is a polar molecule due to the electronegativity difference.
SCN has a linear geometrical shape. I have explained the Lewis structure of SCN in detail, theoretically and practically, in the video.
Its hybridization is sp, because of the highest valence electrons and least electronegativity.
The ligand of SCN is Ambidentate, and the charge of SCN is -1.
If you want to know more about SCN in detail, then read about its properties, uses, and sources.
Do you think we have missed something about the SCN topic? Let us know in the comments section below we will add them.