Hydrogen Peroxide (H2O2) Lewis Structure - Chemistry School

Hydrogen Peroxide (H2O2) Lewis Structure

Lewis structure of Hydrogen peroxide (H2O2) contains two O-H bonds and one O-O bond. Also, there are two lone pairs on each oxygen atom. Concept of number of total valence electrons of oxygen and hydrogen atoms are used to draw lewis structure of H2O2. Each step of drawing lewis structure of H2O2 is explained in detail in this tutorial.

H2O2 lewis structure

There are two hydrogen atoms and two oxygen atoms in H2O2. A hydrogen atom is made a bond with one oxygen atom. There is a single bond between two oxygen atoms and each oxygen atom has two lone pairs.

Steps of drawing lewis structure of H2O2

When we draw a lewis structure, there are several steps to follow. Number of steps can be changed according the complexity of the molecule or ion. Because H2O2 molecule is a simple molecule and there is no overall charge, some of these steps are not required to use. However those all steps are mentioned and explained in detail in this tutorial.

1. Find total number of electrons of the valance shells of hydrogen atoms and oxygen atom
2. Total electrons pairs existing as lone pairs and bonds
3. Center atom selection
4. Mark lone pairs on atoms
5. Mark charges on atoms if there are charges.
6. Check the stability and minimize charges on atoms by converting lone pairs to bonds to obtain best lewis structure.

Important: Drawing correct lewis structure is important to draw resonance structures correctly.

Total number of electrons of the valance shells of H2O2

There are two kind of elements in hydrogen peroxide; hydrogen and oxygen. Hydrogen is a group IA element in the periodic table and only has one electron in its last shell (valence shell). Oxygen is a group VIA element in the periodic table and contains six electrons in its last shell. Now, we know how many electrons are there in valence shells of hydrogen and oxygen atoms.

• valence electrons given by hydrogen atoms = 1 * 2 = 2
• valence electrons given by sulfur atom = 6*2 = 12

• Total valence electrons = 2 + 12 = 14

Total valence electrons pairs

Total valance electrons pairs = σ bonds + π bonds + lone pairs at valence shells

Total electron pairs are determined by dividing the number total valence electrons by two. For, H2O2, Total pairs of electrons are seven in their valence shells.

Center atom of H2O2

To be the center atom in a molecule, ability of having greater valance is important. Then, from hydrogen and oxygen atoms, which atom has the highest valence? We know, it is oxygen. Maximum valence of oxygen is two as explained earlier. Hydrogen's only valence is one. Therefore, oxygen atom should be the center atom of H2O2. So, we can construct the sketch of H2O2 as below. This sketch shows how atoms are connected with each other in the H2O2 molecule.

Lone pairs on atoms

After determining the center atom and sketch of H2O2 molecule, we can start to mark lone pairs on atoms. Remember that, there are total of seven electron pairs.

• There are already three bonds in the drawn sketch (two O-H bonds and one O-O bond). Now only four (7-3) electron pairs are remaining to mark on atoms.
• Usually, those remaining electron pairs should be started to mark on outside atoms. But in H2O2, hydrogen atom are the outside atoms which cannot keep more than two electron in its last shell. There are already two electrons in hydrogen atoms. Therefore, we cannot mark those four electrons pairs on hydrogen atoms.
• Therefore, mark those four electrons pairs on center atoms; oxygen atoms. Each oxygen atom will take two lone pairs to fulfill the octal.

Mark charges on atoms

There are no charges on oxygen atoms and hydrogen atoms. Also, remember that H2O2 is a molecule which does not have a charge. Therefore, not having charges on every atoms tells us we have drawn the lewis structure to a good level. But, we need to make sure, this is the best structure.

Check the stability and minimize charges on atoms by converting lone pairs to bonds

Because there are no charges on atoms, no need to worry about reducing charges as a step of obtaining the best lewis structure. Therefore, we have already got the best lewis structure for H2O2.

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What are the differences of lewis structures of H2O2 and H2O?

• There is an additional oxygen atom in H2O2 molecule. Therefore, lewis structures of H2O2 molecule is different from the arrangement of atoms respective to the H2O molecule.
• However, shape around the oxygen atoms is bent in all two molecules.

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