C3H6 Lewis Structure, Hybridization, Molecular Geometry, Polarity

C3H6 Lewis structure contains three carbon atoms bonding with six hydrogen atoms, all these are bonded with the 7 single bonds and 1 double bond. The lewis structure of C3H6 has 18 bonding electrons and zero non-bonding electrons.

The drawing of the Propene (C3H6) lewis structure is an easy and simple process.

Let’s see how to do it.

Follow some steps for drawing the lewis dot structure for C3H6

1. Count total valence electron in C3H6

Finding the total valence electrons in the molecule is our topmost priority for drawing the lewis diagram. Valence electrons are the outermost electrons of an atom that can help in the formation of the chemical bond.

Now we have to find the valence electron in the C3H6 molecule. To do this, look at the group number of carbon and hydrogen.

As the carbon atom belongs to group 14th in the periodic table and hydrogen is situated in the 1st group, hence, the valence electron for carbon is 4 and for the hydrogen atom, it is only 1.

⇒ Total number of the valence electrons in carbon = 4

⇒ Total number of the valence electrons in hydrogen = 1

∴ Total number of valence electron available for the C3H6 Lewis structure = 4(3) + 1(6) = 18 valence electrons         [∴ C3H6 molecule has three carbon and six hydrogen atoms]

2. Find the least electronegative atom and place it at center

An atom with a less electronegative value is more preferable for the central position in the lewis diagram because they are more prone to share the electrons with surrounding atoms.

So, in the C3H6 molecule, two types of atoms are present – Hydrogen and Carbon. It should be noted that in the lewis diagram, hydrogen atoms always go outside means they always hold the place of the surrounding position, no matter what’s the situation is.

The hydrogen can never be the central atom since it can form a maximum of one covalent bond.

Therefore, place all three carbon atoms are in a central position and all six hydrogens at surrounding to it as shown in the figure below.

3. Connect outer atoms to central atom with a single bond

In the third step, draw a single bond to connect all outer atoms to the central atom.

So, in the case of the C3H6 molecule, place the single bond between each carbon and hydrogen atom. also, connect all three carbon atoms with each other by a single bond.

That’s all, now count the valence electrons used in the above structure.

A single bond contains two electrons, and, in the above structure, 8 single bonds are used, hence, (8 × 2) = 16 valence electrons are used in the above structure.

We had a total of 18 valence electrons available for the C3H6 Lewis structure, and in the above structure, we used 16 valence electrons.

∴ (18 – 16) = 2 valence electrons

So, we are left with 2 valence electrons.

4. Complete the octet of all atoms

“The octet rule refers to the tendency of atoms to prefer to have eight electrons in the valence shell. When atoms have fewer than eight electrons, they tend to react and form more stable compounds.” [Exception may occur]

The hydrogen atom is an exception to the octet rule as it only needs two electrons to fulfill the outermost shell.

So, in the C3H6 molecule, there is hydrogen and carbon, the hydrogen atom needs only 2 electrons to fulfill the octet whereas the carbon prefers 8 electrons in its valence shell to attain stability.

Looking at the 3rd step structure, we see, that all hydrogens already have two electrons(one single bond) in their valence shell, hence, they already completed the octet.

Now check for carbon atoms, the right side carbon has attached with four bonded pairs means it has 8 electrons in its valence shell, hence, it complete the octet.

But the thing is, the middle and left side carbon is only attached with 3 bonded pairs each(check-in 3rd step structure), which means, they have only 6 electrons in their valence shell, so, they are short of 2 electrons for octet.

We know, we have 2 remaining valence electrons, with that 2 valence electrons we can make one bond pair.

All we have to do is that place the 2 remaining valence electrons in form of bonded pair in between the left side carbon and middle side carbon.

C3H6 Lewis structure

As you see in the above figure, the middle and left side carbon has attached with 1 double bond and 2 single bonds, which means, now they have 8 electrons in their valence shell, hence, they completed their octet also.

Also, we have used all the valence electrons that are available for drawing the lewis structure of C3H6.

Now we will check the formal charge for the above structure.

5. Check the stability with the help of a formal charge concept

The lesser the formal charge on atoms, the better is the stability of the lewis diagram.

To calculate the formal charge on an atom. Use the formula given below-

⇒ Formal charge = (valence electrons – nonbonding electrons –  1/2 bonding electrons)

Nonbonding electrons mean lone pair electrons, there is zero lone pair in the C3H6 Lewis structure.

Let’s count the formal charge on the hydrogen atom first, all hydrogen atoms in the C3H6 Lewis structure(4th step) have the same bonded electrons, so, just count the F.C. for the one hydrogen atom.

For hydrogen atom:

⇒ Valence electrons of hydrogen = 1

⇒ Nonbonding electrons on hydrogen= 0

⇒ Bonding electrons around hydrogen(1 single bond) = 2

∴ (1 – 0 – 2/2) = 0 formal charge on all hydrogen atoms.

 For the right side carbon atom

⇒ Valence electrons of carbon = 4

⇒ Nonbonding electrons on carbon = 0

⇒ Bonding electrons around carbon (4 single bonds) = 8

∴ (4 – 0 – 8/2) = 0 formal charge on the right side carbon atom.

 For the left side carbon atom

⇒ Valence electrons of carbon = 4

⇒ Nonbonding electrons on carbon = 0

⇒ Bonding electrons around carbon (2 single bond + 1 double bond) = 8

∴ (4 – 0 – 8/2) = 0 formal charge on the left side carbon atom, the middle one has also zero formal charges.

So, the above lewis structure of propene (C3H6) is the best and most stable as all atoms have zero formal charges.

Also check – 

• Formal charge calculator
• Lewis structure calculator
• How to draw a lewis structure?