C2H5OH (Ethanol) Lewis Structure in 6 Steps

So you have seen the above image by now, right?

Let me explain the above image in short.

C2H5OH (Ethanol) lewis structure has Carbon atoms (C) at the center which is surrounded by Hydrogen atoms (H) and one OH group. There are five C-H bonds, one O-H bond and one C-O bond. There are 2 lone pairs on the Oxygen atom (O).

If you haven’t understood anything from the above image of C2H5OH lewis structure, then just stick with me and you will get the detailed step by step explanation on drawing a lewis structure of C2H5OH (ethanol).

So let’s move to the steps of drawing the lewis structure of C2H5OH (ethanol).

Steps of drawing C2H5OH lewis structure

Step 1: Find the total valence electrons in C2H5OH molecule

In order to find the total valence electrons in a C2H5OH molecule, first of all you should know the valence electrons present in carbon atom, hydrogen atom as well as oxygen atom.
(Valence electrons are the electrons that are present in the outermost orbit of any atom.)

Here, I’ll tell you how you can easily find the valence electrons of carbon, hydrogen as well as oxygen using a periodic table.

Total valence electrons in C2H5OH molecule

→ Valence electrons given by carbon atom:

Carbon is group 14 element on the periodic table. ^[1] Hence the valence electrons present in carbon is 4.

You can see the 4 valence electrons present in the carbon atom as shown in the above image.

→ Valence electrons given by hydrogen atom:

Hydrogen is group 1 element on the periodic table. ^[2] Hence the valence electron present in hydrogen is 1.

You can see that only 1 valence electron is present in the hydrogen atom as shown in the above image.

→ Valence electrons given by oxygen atom:

Oxygen is group 16 element on the periodic table. Hence the valence electrons present in oxygen is 6.

You can see the 6 valence electrons present in the oxygen atom as shown in the above image.

Hence, 

Total valence electrons in C2H5OH molecule = valence electrons given by 2 carbon atom + valence electrons given by 6 hydrogen atoms + valence electrons given by 1 oxygen atom = 4(2) + 1(6) + 6 = 20.

Step 2: Select the central atom

For selecting the center atom, you have to remember that the atom which is less electronegative remains at the center.

(Remember: If hydrogen is present in the given molecule, then always put hydrogen outside.)

Now here the given molecule is C2H5OH and it contains carbon atom (C), hydrogen atoms (H) and oxygen atom (O).

So as per the rule we have to keep hydrogen outside.

Now, you can see the electronegativity values of carbon atom (C) and oxygen atom (O) in the above periodic table.

If we compare the electronegativity values of carbon (C) and oxygen (O) then the carbon atom is less electronegative.

So here the carbon atoms (C) are the center atom and the oxygen atom (O) is the outside atom.

Step 3: Connect each atoms by putting an electron pair between them

Now in the C2H5OH molecule, you have to put the electron pairs between the carbon (C) atom, oxygen (O) atom and hydrogen (H) atoms.

This indicates that these atoms are chemically bonded with each other in a C2H5OH molecule.

Step 4: Make the outer atoms stable

Now in this step, you have to check the stability of the outer atoms.

Here in the sketch of C2H5OH molecule, you can see that the outer atoms are hydrogen atoms and oxygen atom.

These hydrogen atoms and oxygen atom are forming a duplet and octet respectively and hence they are stable.

Also, in step 1 we have calculated the total number of valence electrons present in the C2H5OH molecule.

The C2H5OH molecule has a total 20 valence electrons and all these valence electrons are used in the above sketch of C2H5OH.

Hence there are no remaining electron pairs to be kept on the central atom. 

So now let’s proceed to the next step.

Step 5: Check the octet on the central atom

In this step, you have to check whether the central carbon atoms (C) are stable or not.

In order to check the stability of the central carbon (C) atoms, we have to check whether they are forming an octet or not.

You can see from the above picture that both the carbon atoms are forming an octet. That means they have 8 electrons.

And hence the central carbon atoms are stable.

Now let’s proceed to the final step to check whether the lewis structure of C2H5OH is stable or not.

Step 6: Check the stability of lewis structure

Now you have come to the final step in which you have to check the stability of lewis structure of C2H5OH.

The stability of lewis structure can be checked by using a concept of formal charge.

In short, now you have to find the formal charge on carbon (C) atoms, hydrogen (H) atoms as well as oxygen (O) atom present in the C2H5OH molecule.

For calculating the formal charge, you have to use the following formula;

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

You can see the number of bonding electrons and nonbonding electrons for each atom of C2H5OH molecule in the image given below.

For Carbon (C) atom:
Valence electrons = 4 (because carbon is in group 14)
Bonding electrons = 8
Nonbonding electrons = 0

For Hydrogen (H) atom:
Valence electron = 1 (because hydrogen is in group 1)
Bonding electrons = 2
Nonbonding electrons = 0

For Oxygen (O) atom:
Valence electrons = 6 (because oxygen is in group 16)
Bonding electrons = 4
Nonbonding electrons = 4

Formal charge	=	Valence electrons	–	(Bonding electrons)/2	–	Nonbonding electrons
C	=	4	–	8/2	–	0	=	0
H	=	1	–	2/2	–	0	=	0
O	=	6	–	4/2	–	4	=	0

From the above calculations of formal charge, you can see that the carbon (C) atoms, hydrogen (H) atoms as well as oxygen (O) atom have a “zero” formal charge.

This indicates that the above lewis structure of C2H5OH is stable and there is no further change in the above structure of C2H5OH.

In the above lewis dot structure of C2H5OH, you can also represent each bonding electron pair (:) as a single bond (|). By doing so, you will get the following lewis structure of C2H5OH.

I hope you have completely understood all the above steps.

For more practice and better understanding, you can try other lewis structures listed below.

Try (or at least See) these lewis structures for better understanding:

BeF2 lewis structure	OH- lewis structure
N2H2 lewis structure	CH3Cl lewis structure
HBr lewis structure	N2H4 lewis structure