C2H2 is a chemical formula for Ethyne, a gaseous alkyne hydrocarbon. It has been used widely for welding and cutting purposes. This molecule is also known by the name Acetylene. The compound has a simple structure and is made up of two carbon atoms and two hydrogen atoms. 

Name of moleculeEthyne ( C2H2)
No of Valence Electrons in the molecule10
Hybridization of C2H2sp hybridization
Bond Angles180°
Molecular Geometry of C2H2Linear

In this blog post, we will learn about the total number of valence electrons for C2H2, its Lewis Structure, Molecular Geometry, Shape and more. 


C2H2 Valence electrons

The electrons present in the atoms’ outer shell are the ones that participate in bond formation with other atoms in the molecule. These electrons are known as the valence electrons. To draw a Lewis Structure of any molecule and understand the bond formation in any molecule, it is essential to know the total number of valence electrons.

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Valence electrons in C2H2: Valence electrons of Carbon atom + Valence electrons of Carbon atom

The carbon atom has four valence electrons in its outer shell, but here as there are two Carbon atoms we will multiply the number by 2. Hence there are eight valence electrons for Carbon atoms.

A Hydrogen atom has one valence electron in its outer shell; we will multiply it by two as there are two Hydrogen atoms. So there are two valence electrons for Hydrogen atoms. 

Valence electrons in C2H2: 8 + 2

= 10

There are ten valence electrons in C2H2 molecule.

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C2H2 Lewis Structure

Lewis Structure of any molecule helps to know the arrangement of all atoms, their valence electrons, and the bond formation in the molecule. The electrons that participate in forming bonds are called bonding pairs of electrons while the ones that do not take part in any bond formation are called lone pairs or non-bonding pairs of electrons.

For C2H2 Lewis structure, we will first place both the Carbon atoms in the centre as it is less electronegative than the Hydrogen atoms. Here both the Carbon atoms take the central position, and the Hydrogen atoms are arranged around it.

If you look at the Hydrogen atoms, it only needs one valence electron to attain a stable structure. Here, both the Hydrogen atoms will share one valence electron of the Carbon atom and form a bond.

The octets of both the Hydrogen atoms are now complete, but Carbon atoms still don’t have a complete octet. To attain a stable structure, the Carbon atoms will share their remaining three valence electrons by forming a triple bond.

Note: A total of six valence electrons is used to form a triple bond between both the Carbon atoms.

In Lewis structure of C2H2, the octets of all the atoms are complete, and there are no lone pairs of electrons in the molecule.

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C2H2 Molecular Geometry

The Lewis structure of C2H2 helps us understand the geometry of the molecule. All the atoms here lie in the same plane, and there is no asymmetry in the molecule. As all the atoms are arranged symmetrically in the same plane, C2H2 has a linear molecular geometry. 

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C2H2 Hybridization

To make it easier for you to understand, consider this molecule made up of two CH atoms. Carbon atom’s electron configuration in its ground state is 1s2 2s2 2p2, but when it is in its excited state, the electron from the 2s orbital moves to the 2pz orbital. This hybridized molecule accommodates the shared electron of the Hydrogen. The 1s orbital of the Hydrogen atom overlaps with the Carbon atom’s 2p orbital atom, making it an sp hybridization. There is the formation of one hybridized s and p orbital. This is the same for the other set of CH molecules too. 

Carbon atoms form sigma bonds with each other when one sp orbital overlaps with the sp orbital of the other CH molecule. C-H bonds are created when the second sp orbital overalls with the 1s orbital of the Hydrogen atom. There are two-half filled 2p orbitals for each Carbon atom. These two orbitals form two pi bonds that result in the formation of triple bonds between carbon atoms.

Hence, the Carbon atom has sp hybridization in the C2H2 molecule. 

C2H2 Bond Angles

All the atoms are arranged symmetrically as both the Carbon atoms form a single bond with Hydrogen atoms. The bond angle in C2H2 is 180 degrees. 

C2H2 Shape

C2H2 has a linear shape given its molecular geometry is linear and all the atoms are arranged symmetrically.

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Concluding Remarks

To summarize this article on C2H2 Lewis structure, we can say that,

There are ten valence electrons for Ethyne.Carbon atom forms a single bond with one Hydrogen atom and a triple bond with another Carbon atom.As all the valence electrons are used up in the structure, there are no unshared electrons.It has sp hybridization with a bond angle of 180 degrees.

To find out about the polarity of C2H2, you can check out our detailed blog post on C2H2 polarity.