H3O+ Lewis Structure, Geometry, Hybridization, and MO Diagram - Techiescientist (2024)

The cation H3O+ is known as the hydronium ion. If we see the nomenclature of hydronium ion, we get to know that according to the IUPAC nomenclature, hydronium ion can be referred to as oxonium.

Oxonium is a generalized name for all trivalent oxygen cations, so the use of the name hydronium is necessary to identify hydronium ions particularly.

The molar mass of the hydronium ion is 19.02 g/mol.

The production of this ion is during the protonation of water;

H2O (Water) + H+ (Hydrogen ion) —–> H3O+

This ion is used in determining the pH of water. As water dissociates into OH- and H3O+ and we can check the pH of the water using a particular process.

The hydronium ion is used in various reactions and the production of different compounds. Both organic and inorganic chemistry includes hydronium ion to a large extent.

But before reading the use of this ion in different reactions, we must have knowledge about the basics of this ion, like, lewis structure, geometry, etc.

Knowing these basics will deepen our knowledge about this ion more. We should always try to know the background of any compound before studying any reaction regarding it.

So let’s dig deep and know about some interesting information about hydronium ion!

Contents show

H3O+ Lewis Structure

Let’s try to draw the lewis structure of H3O+.

First of all, we need to calculate the total number of valence electrons present in hydronium ion.

Hydrogen = 1
3*Hydrogen = 3
Oxygen = 6
Total = 9

Now the important point is, not to forget about the + sign. + sign indicates losing an electron from the total valence electrons.
( – sign indicates gaining an electron)

Thus, the total valence electron is 8 now.

Secondly, we need to determine a central atom which is generally the atom with the most available sites for bonding. In this case, Oxygen is the central atom.

Next, we need to draw a skeletal structure of H3O+ with single bonds only. After that, to complete the lewis structure of H3O+ we have to fill up the octet of atoms with the remaining electrons.

At the end of drawing the lewis structure of H3O+, we should check that, all the atoms are having their lowest possible formal charge.

The attached image below shows the lewis structure of hydronium ion;

H3O+ Lewis Structure, Geometry, Hybridization, and MO Diagram - Techiescientist (1)

How to draw Lewis Structure

A lewis structure helps us to find out about the structure of the compound, types, and the number of bonds, physical properties, and how the compound interacts with other compounds.

Drawing a lewis structure is pretty simple!

There is a common way by which we can draw the lewis structure of any compound. To simplify the process more for you, I have jotted down the steps below in bullets :

  • Calculate the total number of valence electrons in the molecule. Do take care of +, – signs while calculating.
  • Choose a central atom; generally the atom with the highest bonding sites.
  • Draw a skeletal structure with single bonds only.
  • Fillup the octet of the atoms with the remaining electrons. Keep in mind to start with the electronegative atoms and proceed to the electropositive one.
  • Give multiple bonds if required for fulfilling the octet of the atoms.
  • At last, make sure all the atoms are having their lowest possible formal charge. You can calculate the same with the formula given below:-

H3O+ Lewis Structure, Geometry, Hybridization, and MO Diagram - Techiescientist (2)

Lewis structure rules are almost the same for all molecules, although some exceptions exist here as well. Chemistry is all about exceptions after all !!

H3O+ Hybridization

The hybridization of H3O+ (hydronium ion) is Sp3.

The hybridization of any molecule can be found using a formula.

H = ½ [ V+M-C+A]

Here,
H= Hybridization
V= No. of valence electrons
M= no. of monovalent atom
C= charge of the cation
A= charge of the anion

If, H= 2 = Sp hybridization
H= 3 = Sp2 hybridization
H= 4 = Sp3 hybridization
H= 5 = Sp3d hybridization
H= 6 = Sp3d2 hybridization

Now let’s find the hybridization of H3O+ using this formula,

In hydronium ion, the central atom is oxygen and it has 6 valence electrons.
Thus by the formula, V = 6

3 hydrogen atoms are bonded to oxygen, so the number of the monovalent atoms (M) = 3
As this is a cationic molecule thus, C = 1

So, H = ½ [ 6 + 3 – 1] = 4

Thus we can say hybridization of H3O+ is Sp3.

Hybridization is generally the mixing of atomic orbitals to form a new hybrid orbital.

We can determine the hybridization of a molecule from the VSEPR chart as well, which we will discuss in the next part.

H3O+ Molecular Geometry

The molecular shape of H3O+ is a trigonal pyramid and electronic geometry is tetrahedral.

H3O+ Lewis Structure, Geometry, Hybridization, and MO Diagram - Techiescientist (3)

From the above chart, we can see that hydronium ion is a AX3E type molecule
(A= central atom, X= bonded atom, E= lone pair on A).

So according to the VSEPR chart, H3O+ has trigonal pyramid as its molecular shape and tetrahedral as its electron geometry.

The image attached below explains all the above-mentioned concept,

H3O+ Lewis Structure, Geometry, Hybridization, and MO Diagram - Techiescientist (4)

Now there is a clear difference between molecular shape and electronic geometry.

In a molecular shape, only the atoms are taken into consideration while determining the structure of the molecule.

But in electron geometry, all electron pairs are taken into consideration.

In other words, lone pairs are taken into consideration in the case of electron geometry and not in molecular shape.

From the VSEPR chart, hybridization can also be determined as I stated earlier. And we can see from here as well that hydronium ion has Sp3 hybridization.

The reason for the polarity also emerges due to the presence of lone pair on the oxygen atom in the H3O+ molecule.

The net dipole comes out to be some non-zero value that makes H3O+ a polar molecule.

H3O+ Molecular Orbital (MO) Diagram

A molecular orbital diagram of any molecule gives us an idea about the mixing of orbitals in the molecule.

Talking about the overlap diagram of H3O+, it is almost similar to H2O but with one electron less and one hydrogen more.

Given below is the image of the molecular orbital diagram of H3O+ and also that of H2O for reference.

H3O+ Lewis Structure, Geometry, Hybridization, and MO Diagram - Techiescientist (5)

In the above image, On the left-hand side, the MO diagram of hydronium ion is explained.

The MO consists of the atomic orbitals of 3 hydrogens. Moreover, the atomic orbital of O+ has one electron less than that in water.

Together they make the MO of the molecule with 2 electrons in the non-bonding orbital.

Also, the bonding orbital is fulfilled with 6 electrons and antibonding is empty.

The image also contains the MO diagram of OH- for reference.

From the molecular orbital diagram, we can see that only sigma bonding is happening in hydronium ion, this indicates that only head-on overlap is possible in this ion.

This is the explanation of the molecular orbital diagram of hydronium ion.

A MO diagram helps us to find the bonding order of a compound which in result gives us information like bond length, the stability of the compound.

Conclusion

This article revolves around the structure, bonding, and hybridization of hydronium ions. The molecular orbital diagram is explained as well.

There are several uses of hydronium ion as I explained earlier. Learning the basics will help you to understand the reactions more and have a clear picture of the hydronium ion. After this, you can easily understand all other things related to hydronium ions.

I hope the article was helpful in some way or the other and hope you gained some knowledge at the end!

If there is any query, feel free to ask me and have a happy reading!

H3O+ Lewis Structure, Geometry, Hybridization, and MO Diagram - Techiescientist (2024)

FAQs

What is the hybridization and geometry of H3O+? ›

Hybridization of H3O+ is sp3 and it's geometry is tetrahedral. Answer: The hybridisation in the central atom of is and geometry is trigonal pyramidal.

How to make H3O? ›

Sometimes, if another molecule like hydrogen chloride (HCl) is dissolved in water, the hydrogen will dissociate as H+. In an aqueous solution, the added H+ becomes attracted to the negative poles on another water molecule. This leaves an H2O molecule with an extra hydrogen atom, written as H3O, called a hydronium ion.

What is the geometric form of H3O+? ›

The geometry of H 3 O + ion is

The shape of H 3 O + is pyramidal as the '3' hydrogen atoms lie at three corners of oxygen as a triangle, and one lone pair of electrons on oxygen attains a pyramidal shape.

What is the shape and geometry of the hydronium ion? ›

The hydronium ion has a trigonal pyramidal geometry and is composed of three hydrogen atoms and one oxygen atom. There is a lone pair of electrons on the oxygen giving it this shape.

What is the shape and structure of H3O+? ›

Hi! H3O+ has a molecular geometry of tetrahedral, since there are 4 regions of electron density surrounding the central O atom (3 Hydrogens and 1 lone pair of electrons). The VSEPR shape would be trigonal pyramidal.

What is the molecular shape and bond angle of H3O+? ›

What is the shape of H3O+ ion? Its pyramidal with 1 set of lone pairs around the oxygen. Bond angle: 115 degrees or anything greater than 109.

Is H3O trigonal pyramidal? ›

The molecular geometry of the H3O+ ion is trigonal pyramidal, which is a tetrahedron missing a vertex due to the presence of three bond pairs and one lone pair on the oxygen atom.

What is the hybridization of the oxygen atom H3O+? ›

The oxygen (O) atom in H 3 O + is hybridized.

As we can see, the central O atom has 4 electron domains (1 lone pair, 3 single bonds). Atoms with 4 electron domains are s p 3 hybridized because one s and three p orbitals hybridize to form 4 s p 3 hybrid orbitals.

What is the molecular geometry of HF? ›

What is the molecular geometry of HF? Hydrogen fluoride has a linear molecular geometry. It has a diatomic composition, and this is the only structure possible when there are only two atoms in a molecule.

How many valence electrons are in the Lewis structure of H3O+? ›

There are 8 valence electrons for the H3O+ Lewis structure. Note that the + sign in the Lewis structure for H3O+ means that we have lost a valence electron. Therefore we only have 8 valence electrons for the H3O+ Lewis structure.

Does H3O+ have a coordinate bond? ›

Hence in H 3 O + ion has two covalent and one covalent coordinate bond.

Why is H3O+ not a Lewis acid? ›

No, H3O+ is not a Lewis acid. To be a Lewis acid the molecule or ion should possess a vacant orbital or a π-bond, in which it can accept a lone electron pair. Because, according to Lewis concept of acid-base, lone electron pair acceptors are Lewis acids.

What is the hybridization of h20+? ›

The hybridization of water (H2O) is sp3. This means that the oxygen atom in water forms four hybrid orbitals by combining one 2s and three 2p orbitals. These hybrid orbitals then arrange themselves in a tetrahedral geometry around the oxygen atom, providing a stable structure for the water molecule.

What is the hybridization of no3 and H3O+? ›

NO−3 has sp2 hybridization and trigonal planar shape while H3O+ has sp3 hybridization and pyramidal structure.

What is the Vsepr theory to predict the molecular geometry of H3O+? ›

Based on VSEPR Theory (Valence Shell Electron Pair Repulsion Theory) the electron clouds on atoms and lone pair of electrons around the O atom will repel each other. As a result they will be pushed apart giving the H 3 O + molecule a trigonal pyramidal molecular geometry or shape.

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