Hydrogen peroxide is slightly more viscous than water with the chemical formula H2O2. It is unstable and decomposable in the presence of light. It can found in the Human body also.
In this article, we will discuss the Hydrogen peroxide (H2O2) lewis structure, its molecular geometry/shape, bond angle, hybridization, Is H2O2 polar or nonpolar, etc.
In pure form, H2O2 is a colorless liquid with a bitter taste. It is the simplest peroxide with an oxygen-oxygen single bond. H2O2 becomes very dangerous when it is heated to boiling temperature even it can explode and cause severe burns.
Useful properties of Hydrogen peroxide
It is a strong oxidizer agent.
It has a bitter taste.
H2O2 is nonflammable.
It has a boiling point of 150.2 °C and a melting point of −0.43 °C.
It is insoluble in petroleum ether.
Uses of Hydrogen peroxide
It is used to prevent infection on skin caused by cuts or burns.
It is very useful for sterilizing medical equipment.
H2O2 lewis structure is made up of two oxygen and two hydrogen atoms, these atoms made two O-H bonds and one O-O bond. There is a total of 4 lone pairs and 3 bonded pairs are present in the lewis structure of H2O2.
The H2O2 lewis dot structure is very simple and the procedure for drawing it same as the other molecules. Let’s see how to draw this step by step.
Follow some steps to drawing the H2O2 Lewis dot structure
1. Count total valence electron in H2O2
In the first step, we need to calculate how many valence electrons are present in it. So, for this look at the periodic group of hydrogen and oxygen.
As hydrogen has only one electron in its valence shell and oxygen belongs to the 16th group in the periodic table so it has 6 electrons in its valence shell.
⇒ Valence electron of Oxygen = 6
⇒ Valence electron of Hydrogen = 1
∴ Total valence electron available for drawing the H2O2 lewis structure = 1*2 + 2*6 = 14 valence electrons [∴ H2O2 has two oxygen and two hydrogens]
2. Find the least electronegative atom and place it at center
Whenever hydrogen is present in any molecule then it doesn’t matter which atom is less or more electronegative, hydrogen always goes outside in a lewis structure and it needs only two electrons to complete its valence shell.
So, place Hydrogen outside in the lewis diagram and Oxygen in between it.
3. Connect hydrogen and oxygen with a single bond
After placing hydrogen and oxygen, now it’s time to connect them with a single bond for further drawing the H2O2 lewis dot structure.
Now look at the above structure, we use three single bonds to connect oxygen and hydrogen. As we know one single bond contains two electrons.
Hence, three single bonds in the above structure mean we use 6 electrons from total valence electrons(14).
∴ (14 – 6) = 8 valence electrons
Now we are left with 8 valence electrons.
4. Placed remaining valence electrons starting from outer atom first
In this step, we have to place the remaining valence electrons in the above structure starting from the outer atom first.
But in the lewis structure of H2O2, the outer atom is hydrogen and hydrogen only needs two electrons to complete its valence shell.
Also, hydrogen already shared two electrons with the help of a single bond connected with an oxygen atom in the H2O2 structure.
So, placed these remaining valence electrons around oxygen for completing its octet rule.
5. Complete central atom octet and make covalent bond if necessary
This is the final step for drawing the H2O2 lewis structure. In this step place those remaining valence electrons around oxygen atoms and complete its octet rule.
As we have a total of 8 valence electrons remaining and oxygen needs 8 electrons to complete its outer shell. Also, each oxygen shares 4 electrons already with the help of single bonds in between them.
Hence, each oxygen needs only 4 valence electrons around them for completing their octets. So, put the remaining valence electrons on the oxygen atom.
H2O2 lewis structure
Now look at the above H2O2 lewis dot structure, each oxygen has 4 unshared electrons(2 lone pairs) and 4 shared electrons. Hence oxygen satisfied its octet rule and hydrogen has already completed its valence shell or octets.
And no need to make any covalent bond between them because we got our best Hydrogen peroxide lewis structure.
What is the molecular geometry of H2O2 and its Hybridization?
Hydrogen peroxide (H2O2) molecular geometry is bent and it is a non-planar molecule with twisted geometry. Also, it is said that it has an open book structure.
Well, this is true because lone pair electrons on oxygen atoms will repel the electron cloud of another atom as much as they can in order to minimize the repulsion according to the VSEPR theory, as a result, unbounded electron pairs push down the adjacent bonding atoms(hydrogen) and stretch the structure making it look like an open book structure.
Now How to find the molecular geometry of H2O2 theoretically? To find H2O2 molecular geometry we need to see its lewis diagram for determining how many lone pairs and bonded pairs it contains, then we will use the AXN method or VSEPR chart.
Follow three steps to find H2O2 molecular geometry
1. Find the Number of lone pairs present on the central atom of the H2O2 Lewis structure
According to the H2O2 lewis structure, it contains a total of 4 lone pairs and each oxygen(central atom) has 2 lone pairs.
Or you can determine lone pair in H2O2 by using the simple formula
∴ L.P = (V.E. – N.A.)/2
where L.P. = Lone pair on the central atom
⇒ V.E. = valence electron of that central atom
⇒ N.A. = Number of atoms attached to that central atom
So, the central atom we know Its Oxygen and It has 6 valence electrons in its last shell. Also, the number of attached atoms to each oxygen is two(Oxygen and hydrogen).
Therefore, the Lone pair on the left side oxygen is = (6 – 2)/2 = 2 L.P.
and the lone pair on the right side of the oxygen is = (6 – 2)/2 = 2 L.P.
So, the total number of lone pairs present on the central atom of the H2O2 lewis structure is 2 + 2 = 4.
2. Find hybridization number of H2O2
The hybridization of H2O2 is Sp³ and each oxygen atom in H2O2 undergoes Sp³ hybridization because each oxygen contains 2 lone pairs and 2 bond pairs that result in 4 steric numbers.
For finding the hybridization or steric number of H2O2, Use the given below formula.
∴ H = N.A. + L.P.
where H = hybridization number
⇒ N.A. = Number of atoms attached to the central atom
⇒ L.P. = lone pairs on that central atom
As we already know, the number of the attached atom to each oxygen is 2, and lone pairs on each oxygen are also two.
Therefore, H = 2 + 2
∴ H = 4
So, 4 hybridization numbers mean, H2O2 has Sp³ hybridization.
3. Use VSEPR theory or AXN method to determine H2O2 molecular shape/geometry
As we discussed H2O2 molecular shape is bent But you can find it by using the VSEPR(Valence shell electrons repulsion) theory and AXN method also.
According to the VSEPR theory, if any molecule has 2 lone pairs and Sp³ hybridization, then the molecule shape of that molecule is Bent and electron geometry is tetrahedral.
H2O2 molecular geometry/shape
Now it’s time to use another alternative method to determine the molecular geometry of H2O2 that is the AXN method.
Let’s see how to use this method.
A represents the central atom.
X represents the bonded pairs of electrons to the central atom.
N represents the lone pairs of electrons on the central atom
So, A means oxygen and it has attached with two bonded pairs of electrons. Also, lone pairs of electron on the Oxygen is also two.
Hence formula of H2O2 becomes AX2N2.
According to the VSEPR chart, if any molecule represents the AX2N2 formula then the molecule geometry of that molecule is bent and electron geometry is tetrahedral.
Bonded atoms
Lone pair
Generic formula
Hybridization
Molecular geometry
Electron geometry
1
0
AX
S
Linear
Linear
2
0
AX2
Sp
Linear
Linear
1
1
AXN
Sp
Linear
Linear
3
0
AX3
Sp²
Trigonal planar
Trigonal planar
2
1
AX2N
Sp²
Bent
Trigonal planar
1
2
AXN2
Sp²
Linear
Trigonal planar
4
0
AX4
Sp³
Tetrahedral
Tetrahedral
3
1
AX3N
Sp³
Trigonal pyramid
Tetrahedral
2
2
AX2N2
Sp³
Bent
Tetrahedral
1
3
AXN3
Sp³
Linear
Tetrahedral
3
2
AX3N2
Sp³d
T-shaped
Trigonal bipyramidal
The bond angle of H2O2 is approx 94.8º(H–O–O) in the gas phase and 101.9º in solid(crystal) because there is two lone pair present on each oxygen that decreased the angle from the normal value of tetrahedral geometry molecules.
Hydrogen peroxide polarity: Is H2O2 polar or nonpolar?
Many have confusion regarding whether H2O2 is polar or nonpolar? Well, it’s a polar molecule because the molecular geometry of H2O2 is bent and due to the presence of lone pair on the central atom(oxygen), it creates an unequal charge distribution which leads to H2O2 polar in nature.
Let’s understand in detail whether hydrogen peroxide is polar or non-polar.
Three factors that indicate the polarity of H2O2
1. Electronegativity:
Electronegativity means the tendency of an atom to attracting electrons towards itself. If the electronegativity difference between the atoms is high then the polarity will also be higher. Now, look at the electronegativity of hydrogen and oxygen.
As hydrogen electronegativity is around 2.20 and for oxygen it is around 3.45. Therefore oxygen has a higher tendency to attract an electron to itself than hydrogen.
Also, the electronegativity difference between hydrogen and oxygen is more than 0.5, and according to the Pauling scale if the electronegativity difference between atoms is higher than 0.5 then that molecule will be polar in nature. Hence H2O2 is polar in nature.
2. Dipole moment
Dipole moment ensures the strength of polarity between hydrogen and oxygen atom. The electronegativity difference between these atoms induced positive and negative charges.
As oxygen is more electronegative than hydrogen hence some negative charge is induced around oxygen and a partial positive charge is induced around hydrogen. So, these charges create two dipole moments around O–H bond in the H2O2 lewis structure which will not cancel out because they are lying in two different planes.
So, the sum of two O–H bonds cannot be zero and it provides some dipole moment which leads hydrogen peroxide to become polar in nature.
3. Geometrical or molecular shape:
The geometrical structure of any molecule has great influences on the polarity nature. As the molecular geometry of H2O2 is bent and electron geometry is tetrahedral it shows that dipoles cannot be canceled out because they lie in two different planes.
Also, lone pair present in the Hydrogen peroxide lewis structure cause uneven charge distribution around atoms that makes the H2O2 structure Non-planar.
So, all these factors show Why H2O2 is a Polar molecule.
What is the formal charge in the H2O2 lewis structure and how to calculate it?
The formal charge shows that which atom has more positive or negative charge present on it.
To calculate the formal charge in H2O2 lewis dot structure, Use the given formula-
Now we will calculate the formal charge on the central atom which is Oxygen in the H2O2 molecule.
⇒ Valence electron of Oxygen = 6
⇒ Bonding electrons = 4
⇒ Non-bonding electrons(lone pairs electrons) = 4
Put these in formal charge formula-
∴ (6 – 4 – 4/2)
= 0 is the formal charge on the central atom(Oxygen).
FAQ
How many bonded pair and unbonded pair electrons are present in the H2O2 lewis dot structure?
As per the H2O2 lewis structure, a total of four lone pairs are present around oxygen atoms and three bonded pairs are present in between two hydrogens.
So, the total number of unbonded pair electrons = 4*2 = 8
and the total number of bonded pair electrons = 3*2 = 6
Why the H2O2 lewis structure molecular geometry is bent and electron geometry is tetrahedral?
The electron geometry of H2O2 is tetrahedral because each oxygen in the H2O2 lewis structure has an Sp³ hybrid which adopts a tetrahedral structure.
Whereas molecular geometry of H2O2 is bent because the presence of lone pair on oxygen causes the O–H bond in the H2O2 lewis structure to be pushed downward and upward directions.
Always remember more the lone pair, the greater is the degree of the bent shape of the molecule. As the lewis dot structure of H2O2 contains 4 lone pairs hence it is a non-planar and bent structure.
Summary
Let’s take a quick overview of H2O2 lewis’s structure and molecular geometry for its happy ending.
The total valence electron in H2O2 is 14.
Hydrogen peroxide lewis structure is made up of two oxygen and two hydrogen atoms, these atoms made two O-H bonds and one O-O bond.
The total lone pair present in the H2O2 lewis dot structure is 4.
H2O2 molecular geometry is bent and electron geometry is tetrahedral.
The bond angle of H2O2 in the gas phase is 94.8º and in the solid phase, it is 101.9º.
Hydrogen peroxide is polar in nature and has a non-planar structure.
The dipole moment of hydrogen peroxide is around 2.1 Debye.
The formal charge in the H2O2 lewis structure is zero.
