H2O Lewis structure

H₂O (water) has two hydrogen atoms and one oxygen atom.

In the H₂O Lewis structure, there are two single bonds around the oxygen atom, with two hydrogen atoms attached to it, and on the oxygen atom, there are two lone pairs.

Alternative method: Lewis structure of H₂O

Contents

Rough sketch

First, determine the total number of valence electrons

In the periodic table, hydrogen lies in group 1, and oxygen lies in group 16.

Hence, hydrogen has one valence electron and oxygen has six valence electrons.

Since H₂O has two hydrogen atoms and one oxygen atom, so…

Valence electrons of two hydrogen atoms = 1 × 2 = 2
Valence electrons of one oxygen atom = 6 × 1 = 6

And the total valence electrons = 2 + 6 = 8

Learn how to find: Hydrogen valence electrons and Oxygen valence electrons

Second, find the total electron pairs

We have a total of 8 valence electrons. And when we divide this value by two, we get the value of total electron pairs.

Total electron pairs = total valence electrons ÷ 2

So the total electron pairs = 8 ÷ 2 = 4

Third, determine the central atom

Here hydrogen can not be the central atom. Because the central atom is bonded with at least two other atoms, and hydrogen has only one electron in its last shell, so it can not make more than one bond.

Hence, here we have to assume that the central atom is oxygen.

Therefore, place oxygen in the center and hydrogens on either side.

And finally, draw the rough sketch

Rough sketch of H₂O Lewis structure | Image: Learnool

Lone pair

Here, we have a total of 4 electron pairs. And two O — H bonds are already marked. So we have to only mark the remaining two electron pairs as lone pairs on the sketch.

Also remember that hydrogen is a period 1 element, so it can not keep more than 2 electrons in its last shell. And oxygen is a period 2 element, so it can not keep more than 8 electrons in its last shell.

Always start to mark the lone pairs from outside atoms. Here, the outside atoms are hydrogens. But no need to mark on hydrogen, because each hydrogen has already two electrons.

So for oxygen, there are two lone pairs.

Mark the lone pairs on the sketch as follows:

Lone pairs marked, and got the stable Lewis structure of H₂O | Image: Learnool

Formal charge

Use the following formula to calculate the formal charges on atoms:

Formal charge = valence electrons – nonbonding electrons – ½ bonding electrons

For each hydrogen atom, formal charge = 1 – 0 – ½ (2) = 0

For oxygen atom, formal charge = 6 – 4 – ½ (4) = 0

Here, both hydrogen and oxygen atoms do not have charges, so no need to mark the charges.

Final structure

The final structure of H₂O features a central oxygen atom connected to two hydrogen atoms through single covalent bonds. In this arrangement, the oxygen atom satisfies the octet rule by maintaining two lone pairs alongside its two bonding pairs. Each hydrogen atom reaches its stable duet state through its single shared bond. This configuration is the most stable because it results in formal charges of zero for all atoms involved, representing the most energetically favorable state for the molecule. Accordingly, this specific electronic distribution serves as the definitive and most accurate Lewis representation of water.

Next: N₂ Lewis structure

External video

Water Lewis Structure – How to Draw the Lewis Structure for Water – YouTube • Wayne Breslyn

External links

Deep

Learnool.com was founded by Deep Rana, who is a mechanical engineer by profession and a blogger by passion. He has a good conceptual knowledge on different educational topics and he provides the same on this website. He loves to learn something new everyday and believes that the best utilization of free time is developing a new skill.