Lewis structure of H2O

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The Lewis structure of H₂O illustrates the molecular arrangement of water, a compound consisting of two hydrogen atoms and one oxygen atom. In this structure, the central oxygen atom is bonded to the two hydrogen atoms through single bonds. The oxygen atom has two lone pairs of electrons, while the hydrogen atoms do not have any lone pairs. The central oxygen atom satisfies the octet rule, while the two hydrogen atoms adhere to the duet rule. There are no formal charges on any of the atoms, indicating that the structure is stable.

To draw this structure, the first step is to calculate the total number of valence electrons and select the central atom, the least electronegative element among the atoms. Using the total number of valence electrons and the chosen central atom, sketch a rough outline of the structure. The second step involves indicating the chemical bonds between the atoms. In the third step, determine the total number of lone pairs, distribute them among the atoms, and mark them accordingly. The fourth step involves completing the octet (or duet for hydrogen) for each atom by distributing the lone pairs to those that do not achieve an octet. In the fifth and final step, calculate the formal charge for each atom, mark these charges on the structure, and assess whether the final structure is stable.

Alternative method: H₂O Lewis structure

Steps

Draw skeleton

In this step, first calculate the total number of valence electrons. And then, decide the central atom.

• Let’s calculate the total number of valence electrons

We know that… hydrogen is a group 1 element and oxygen is a group 16 element. Hence, hydrogen has one valence electron and oxygen has six valence electrons.

Now H₂O has two hydrogen atoms and one oxygen atom.

So the total number of valence electrons = (valence electrons of hydrogen atom × 2) + valence electrons of oxygen atom

Therefore, the total number of valence electrons = 2 + 6 = 8

• Now decide the central atom

We can not assume hydrogen as 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, assume that oxygen is the central atom.

So now, put oxygen in the center and hydrogens on either side. And draw the rough skeleton structure for the Lewis structure of H₂O something like this:

Also read: How to draw Lewis structure of NO₂ (5 steps)

Show chemical bond

Place two electrons between the atoms to show a chemical bond. Since oxygen is surrounded by two hydrogens, use four electrons to show two chemical bonds as follows:

Also read: How to draw Lewis structure of NH₃ (4 steps)

Mark lone pairs

As calculated earlier, we have a total of 8 valence electrons. And in the above structure, we have already used four valence electrons. Hence, four valence electrons are remaining.

Two valence electrons represent one lone pair. So four valence electrons = two lone pairs.

Note 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.

Also, make sure that you start marking these lone pairs on outside atoms first. And then, on the central atom.

The outside atoms are hydrogens. But hydrogen can not keep more than 2 electrons in its last shell. Hence, don’t mark the lone pairs on hydrogen.

So the central atom (oxygen) will get two lone pairs.

Now draw the Lewis structure of H₂O something like this:

In the above structure, you can see that the octet is completed on the central atom (oxygen), and also on the outside atoms. Therefore, the octet rule is satisfied.

After completing the octet, one last thing we need to do is, calculate the formal charge and check the stability of the above structure.

Also read: How to draw Lewis structure of HCN (5 steps)

Calculate formal charge and check stability

The following formula is used to calculate the formal charges on atoms:

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

Collect the data from the above structure and then, write it down below as follows:

• For each hydrogen atom

Valence electrons = 1
Nonbonding electrons = 0
Bonding electrons = 2

Formal charge = 1 – 0 – ½ (2) = 0

• For oxygen atom

Valence electrons = 6
Nonbonding electrons = 4
Bonding electrons = 4

Formal charge = 6 – 4 – ½ (4) = 0

Mention the formal charges of atoms on the structure. So the Lewis structure of H₂O looks something like this:

In the above structure, you can see that the formal charges of both (hydrogen and oxygen) are zero. Therefore, this is the stable Lewis structure of H₂O.

And each horizontal line drawn in the above structure represents a pair of bonding valence electrons.

Next: Lewis structure of NO₂

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Related

• Lewis structure of NO₂
• Lewis structure of NH₃
• Lewis structure of HCN
• Lewis structure of SO₂
• Lewis structure of N₂

External video

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

External links

• Lewis Structure for H2O – The University of Maryland
• H2O Lewis Structure in 6 Steps (With Images) – Pediabay
• H2O Molecular Geometry, Lewis Structure, Shape and Bond Angles – Geometry of Molecules
• H2O Lewis Structure, Molecular Geometry, and Hybridization – Techiescientist
• H2O Lewis structure, Molecular geometry, Bond angle, Shape – Topblogtenz
• Lewis Structure of H2O (Water) – Drawing Steps – Chemistry School
• What is the Lewis structure of H2O? – Socratic
• Lewis structure of water H2O – Chemistry Online
• H2O Lewis structure and Molecular Geometry [No#1 Best Explanation] – Science Education and Tutorials
• What is the Lewis structure of H2O? – Quora
• Molecular Geometry of Water (H2O) – Chemistry Learner
• Lewis Dot of Water H2O – Kent’s Chemistry
• File:H2O Lewis Structure PNG.png – Wikipedia
• The Lewis structure for water – Oklahoma State University
• H2O Lewis Structure, Geometry – Kemicalinfo
• VSEPR calculation for water, OH2 – University of Sheffield
• Chemical Bonding: Water Lewis Structure – The Geoexchange
• Covalent bond and Lewis dot structure (H2O & CO2) (video) – Khan Academy
• The Lewis Dot Structure for H2O – MakeTheBrainHappy
• Lewis Structures| Hydrogen (H2), and Water (H2O) – What’s Insight
• Water (H2O) Lewis Dot Structure – ShowMe
• Chemical Bonding of H2O – Scholarly Community Encyclopedia
• 15.1: Structure of Water – Chemistry LibreTexts
• Draw the Lewis structure of water (H2O) and then determine its electron domain and molecular geometries – Bartleby
• Draw the Lewis structure of H2O – Brainly
• The Lewis Dot Structure For H2o – Lewis Diagram For H2o – SeekPNG
• Draw the Lewis structure for H2O – Numerade
• Draw the lewis electron-dot structure for water – CK-12 Foundation