Hydrogen Cyanide is a colorless, flammable, and also poisonous chemistry liquid. Represented by the chemical formula, HCN is among those molecules that has an exciting Lewis structure. This fluid is offered in electroplating, mining, and as a precursor for several compounds.

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And to additional understand Hydrogen Cyanide’s physical properties, the is vital to know its Lewis structure and molecular geometry. Keep analysis this write-up to uncover out that is shape, polarity, and more. First, let us look at its Lewis dot structure and also the valence electron that take part in developing bonds.

HCN valence electrons

To draw the Lewis dot framework of any molecule, it is necessary to understand the total variety of valence electrons in the structure. To know the valence electrons of HCN, let us go through the valence electron of individual atoms in Hydrogen Cyanide.

This molecule is consisted of of three different atoms: Hydrogen, Carbon, and also Nitrogen. 

Hydrogen has one valence electron, and also it only needs one much more electron to complete its valence covering as that is an exemption to the octet rule. 

So Hydrogen has actually one valence electron.

Whereas Carbon has 4 valence electrons and Nitrogen has 5 valence electrons.

Total number of valence electron in HCN= No. That valence electron in Hydrogen + No. The valence electron in Carbob+ No.of valence electrons in Nitrogen

= 1+4+5

= 10 valence electrons

Hence, Hydrogen Cyanide, HCN, has actually ten valence electrons. 

HCN Lewis structure

Once you acquire the total variety of valence electrons, you have the right to make a Lewis dot framework of HCN. This structure helps in knowledge the arrangement of valence electrons about the atoms in the molecule. It also aids with knowledge the bonds developed in the molecule and also the electrons no participating in any type of bond formation.

To start with make the Lewis structure of HCN, us will very first determine the central atom. And then ar the staying atoms in the structure. 

As Carbon is the the very least electronegative atom in this molecule, it will certainly take the main position. Ar the Hydrogen and also Nitrogen atoms on both terminal sides of the Carbon favor this:

Once you have actually arranged the atoms, begin placing the valence electrons about individual atoms. Like Hydrogen will have actually one electron, Carbon will certainly have 4 electrons, and Nitrogen will have 5 electrons about its atom favor this:

If friend look at the framework closely, you will certainly realize the Hydrogen deserve to share one electron v the Carbon atom and also become stable. So both Carbon and also Hydrogen will certainly share 2 electrons and type a single bond.


Now that we have completed the valence shell for Hydrogen permit us perform the same for the Carbon atom. The atom is left with just three valence electrons together it has actually shared one electron through Hydrogen. And also so Carbon will certainly share its staying three electrons v Nitrogen to complete its octet, bring about the development of a triple bond in between Carbon and also Nitrogen.


Carbon has a finish octet by forming a solitary bond with Hydrogen and a triple bond with the Nitrogen atom. Similarly, Nitrogen has actually a complete octet as it only required three electrons for completing the octet the it got by share the electrons with Carbon. Hydrogen has actually two electrons in its outer valence shell. The remainder two electrons room nonbonding electrons.

HCN molecule Geometry

The molecule Geometry of any given molecule helps know its three-dimensional structure and also the arrangement of atoms in a molecule, and its shape. Hydrogen Cyanide has actually geometry like AX2 molecule, wherein A is the main atom and also X is the variety of atoms bonded through the central atom.

As Carbon is bonded to two atoms, it follows the molecular geometry of AX2. And as every VSEPR theory, molecules spanned under AX2 have actually a linear molecular geometry.

Hence Hydrogen Cyanide has linear molecule geometry. 


HCN bond Angles

Once we understand the Lewis structure and Molecular Geometry of any kind of molecule, that is easy to identify its bond angles and polarity. As this molecule has a straight molecular geometry, HCN has bond angles of 180 degrees.


HCN Shape

As both Hydrogen and Nitrogen space placed much from each other at bond angles of 180 degrees, it creates a direct shape.

HCN Polarity

HCN in a polar molecule, uneven the straight CO2. And also here is why:

Carbon has an electronegativity that 2.5, Hydrogen’s electronegativity is 2.1, and Nitrogen has an electronegativity that 3.

 Although Hydrogen is the the very least electronegative, it have the right to never take a central position. And also due come the difference in electronegativities in between Carbon and also Hydrogen, the vector represents charge will certainly be attracted from Hydrogen to Carbon. Similarly, together Nitrogen is more electronegative than Carbon, the vector will be in the direction of Nitrogen from Carbon.

Despite quite a small difference in Carbon and Nitrogen’s electronegativities, it is considered a slightly polar bond as Nitrogen will try to traction the electrons to itself. Because of such differences, Hydrogen will have slightly positive charges, and also Nitrogen will have slightly negative charges together the vector goes indigenous Hydrogen to Nitrogen.

Thus Nitrogen becomes a an adverse pole, and the Hydrogen atom i do not care a positive pole, make the molecular polar. Any type of molecule that has actually a distinction of electronegativities of any dipole moment is considered as polar.

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Hence, Hydrogen Cyanide is a polar molecule.

Concluding Remarks

To summarize everything in this article, we deserve to say that:

Carbon creates one solitary bond v the Hydrogen atom and forms a triple bond with the Nitrogen atom.HCN has actually a full of 10 valence electrons.It is spanned under AX2 molecule geometry and also has a direct shape.The bond angle of HCN is 180 degrees.Hydrogen Cyanide is a polar molecule.