SO2 Molecular Geometry - Science Education and Tutorials

Q: What is the molecular notation for SO2 molecule?

SO2 molecular notation is AX2N1.

Sulfur dioxide(SO2) has the composition of one sulfur and two oxygen atoms. What is the molecular geometry of sulfur dioxide?. Drawing and predicting the SO2 molecular geometry is very easy by following the given method. Here in this post, we described step by step to construct SO2 molecular geometry. Sulfur and oxygen come from the 16th family group in the periodic table. Sulfur and oxygen have six valence electrons.

Table of Contents

Key Points To Consider When drawing The SO2 Molecular Geometry

A three-step approach for drawing the SO2 molecular can be used. The first step is to sketch the molecular geometry of the SO2 molecule, to calculate the lone pairs of the electrons in the central sulfur and terminal oxygen atoms; the second step is to calculate the SO2 hybridization, and the third step is to give perfect notation for the SO2 molecular geometry.

The SO2 molecular geometry is a diagram that illustrates the number of valence electrons and bond electron pairs in the SO2 molecule in a specific geometric manner. The geometry of the SO2 molecule can then be predicted using the Valence Shell Electron Pair Repulsion Theory (VSEPR Theory) and molecular hybridization theory, which states that molecules will choose the SO2 geometrical shape in which the electrons have from one another in the specific molecular structure.

Finally, you must add their bond polarities characteristics to compute the strength of the two S-O double bonds (dipole moment properties of the SO2 molecular geometry). Two sulfur-oxygen double bonds in the sulfur dioxide(SO2), for example, are polarised toward the high electronegative value oxygen atoms, and because all two (S-O) double bonds have the same size and polarity, their sum is zero due to the SO2 molecule’s bond dipole moment due to pulling the electron cloud to the two side of V-shaped or bent geometry, and the SO2 molecule is classified as a nonpolar molecule.

The molecule of sulfur dioxide(with linear shape SO2 molecular geometry) is tilted at 119 degrees bond angle of O-S-O. It has a difference in electronegativity values between sulfur and oxygen atoms, with oxygen’s pull the electron cloud being higher than sulfur’s. But bond polarity of S-O is not canceled to each other in the V-shaped or bent geometry. As a result, it has a nonzero permanent dipole moment in its molecular structure. The SO2 molecule has a nonzero dipole moment due to an unequal charge distribution of negative and positive charges in the V-shaped or bent geometry.

Overview: SO2 electron and molecular geometry

According to the VSEPR theory, the SO2 molecule possesses linear molecular geometry. Because the center atom, sulfur, has two S-O double bonds with the two oxygen atoms surrounding it. The O-S-O bond angle is 119 degrees in the V-shaped or bent SO2 molecular geometry. The SO2 molecule has a V-shaped or bent geometry because it contains two oxygen atoms in the V-shaped or bent form and two corners with one lone pairs of electrons on central sulfur atom.

There are two S-O double bonds at the SO2 molecular geometry. After linking the two oxygen atoms and one lone pair of electrons on the sulfur atom in the V-shaped or bent form, it maintains the V-shaped or bent structure. In the SO2 molecular geometry, the S-O double bonds have stayed in the two terminals and one lone pair of electrons on the sulfur atom of the V-shaped or bent molecule.

The central sulfur atom of SO2 has one lone pair of electrons, resulting in V-shaped or bent SO2 electron geometry. However, the molecular geometry of SO2 looks V-shaped or bent and has one lone pair of electrons on the sulfur of the SO2 geometry. It’s the SO2 molecule’s asymmetrical geometry. As a result, the SO2 molecule is polar.

How to find SO2 hybridization and molecular geometry

Calculating lone pairs of electrons on sulfur in the SO2 geometry:

1.Determine the number of lone pairs of electrons in the core sulfur atom of the SO2 Lewis structure. Because the lone pairs of electrons on the sulfur atom are mostly responsible for the SO2 molecule geometry planar, we need to calculate out how many there are on the central sulfur atom of the SO2 Lewis structure.

Use the formula below to find the lone pairs on the sulfur atom of the SO2 molecule.
L.P(S) = V.E(S) – N.A(S-O)/2

Lone pair on the central sulfur atom in SO2 = L.P(S)
The core central sulfur atom’s valence electron in SO2= V.E(S)
Number of S-O bonds = N.A (S-O)
calculation for sulfur atom lone pair in SO2 molecule.

For instance of SO2, the central atom, sulfur, has six electrons in its outermost valence shell, two S=O double bond connections. This gives a total of four connections.

As a result of this, L.P(S) = (6 –4)/2=2/2=1

The lone pair of electrons in the sulfur atom of the SO2 molecule is one.

Calculating lone pair of electrons on the terminal oxygen in the SO2 geometry:

Finding lone pair of electrons for the terminal oxygen atom is not similar to the central sulfur atom. We use the following formula as given below

Use the formula below to find the lone pair on the oxygen atom of the SO2 molecule.
L.P(O) = V.E(O) – N.A(S-O)

Lone pair on the terminal oxygen atom in SO2 = L.P(O)
Terminal oxygen atom’s valence electron in SO2 = V.E(O)
Number of S-O bonds = N.A (S-O)
calculation for oxygen atom lone pair in SO2 molecule.

For instance of SO2, their terminal atoms, oxygen, have six electrons in their outermost valence shell, one S-O double bond connection. This gives a total of two S-O double bond connections. But we are considering only one connection for the calculation.

As a result of this, L.P(O) = (6 –2)=4

The lone pair of electrons in the oxygen atom of the SO2 molecule is four. Two oxygen atoms are connected with the central sulfur atom.

In the SO2 electron geometry structure, the lone pairs on the central sulfur atom are one, lone pairs of electrons in the oxygen atom have two pairs(4 electrons). Two oxygen atoms have two lone pairs of electrons.

It means there are two lone pairs of electrons in the core sulfur atom. One lone pair of electrons on the central sulfur atom is responsible for the V-shaped or bent nature of SO2 molecular geometry. But in the structure oxygen atoms are polarised sidewise in their V-shaped or bent geometry.

The two lone pairs of electrons on the terminal oxygen atoms are placed at two ends of the SO2 geometry. Because the sulfur atom is a lower electronegative value as compared with other atoms in the SO2 molecule. Two oxygen atoms are polarized towards the sidewise in the SO2 structure.

But in reality, the SO2 has four lone pairs of electrons on the two oxygen ends in its structure. This makes the SO2 more asymmetrical in the structure of the molecule. Because there is electric repulsion between bond pairs and lone pairs.

SO2 is mainly used as an organic reagent in most of the particular types of organic synthetic reactions. It is a chemical reagent and has a very similar structure to a CO2 molecule. But CO2 is in the gaseous state at normal temperature and pressure. Liquid CO2 is used as a solvent in some extreme reactions. Dry ice is nothing but the solid form of CO2.

But in the central, sulfur atom has one lone pair of electrons, and two S-O bond pairs stay oppose to each other around 119 degrees.

Calculate the number of molecular hybridizations of the SO2 molecule

What is SO2 hybridization? This is a very fundamental question in the field of molecular chemistry. All the molecules are made of atoms. In chemistry, atoms are the fundamental particles. There are four different types of orbitals in chemistry. They are named s, p, d, and f orbitals.

The entire periodic table arrangement is based on these orbital theories. Atoms in the periodic table are classified as follows:

s- block elements
p- block elements
d-block elements
f-block elements
Atoms are classified in the periodic table

SO2 molecule is made of one sulfur, two oxygen atoms. The oxygen and sulfur atoms have s and p orbitals. But oxygen atom has s and p orbitals in the ground state. Oxygen comes as the first element in the periodic table of the oxygen family. The sulfur atom also belongs to the oxygen family group. But it falls as the second element in the periodic table.

When these atoms combine to form the SO2 molecule, its atomic orbitals are mixed and form unique molecular orbitals due to hybridization.

How do you find the SO2 molecule’s hybridization? We must now determine the molecular hybridization number of SO2.

The formula of SO2 molecular hybridization is as follows:
No. Hyb of SO2= N.A(S-O bonds) + L.P(S)
No. Hy of SO2 = the number of hybridizations of SO2
Number of S-O bonds = N.A (S-O bonds)
Lone pair on the central sulfur atom = L.P(S)
Calculation for hybridization number for SO2 molecule

In the SO2 molecule, sulfur is a core central atom with two oxygen atoms connected to it. It has one lone pair of electrons on sulfur. The number of SO2 hybridizations (No. Hyb of SO2) can then be estimated using the formula below.

No. Hyb of SO2= 2+1=3

The SO2 molecule hybridization is two. The sulfur and oxygen atoms have s and p orbitals. The sp2 hybridization of the SO2 molecule is formed when one s orbital and one p orbitals join together to form the SO2 molecular orbital.

Molecular Geometry Notation for SO2 Molecule :

Determine the form of SO2 molecular geometry using VSEPR theory. The AXN technique is commonly used when the VSEPR theory is used to calculate the shape of the SO2 molecule.

The AXN notation of SO2 molecule is as follows:
The central sulfur atom in the SO2 molecule is denoted by the letter A.
The bound pairs (two S-O bonds) of electrons to the core sulfur atom are represented by X.
The lone pairs of electrons on the central sulfur atom are denoted by the letter N.
Notation for SO2 molecular geometry

We know that sulfur is the core atom of SO2, with two electron pairs bound (two S-O) and one lone pair of electrons. The general molecular geometry formula for SO2 is AX2N1.

According to the VSEPR theory, if the SO2 molecule has an AX2N1 generic formula, the molecular geometry and electron geometry will both be V-shaped or bent forms.

Name of Molecule	sulfur dioxide
Chemical molecular formula	SO2
Molecular geometry of SO2	V-shaped or bent
Electron geometry of SO2	V-shaped or bent
Hybridization of SO2	sp2
Bond angle (O-S-O)	119º degree
Total Valence electron for SO2	18
The formal charge of SO2 on sulfur	0

Summary:

In this post, we discussed the method to construct SO2 molecular geometry, the method to find the lone pairs of electrons in the central sulfur atom, SO2 hybridization, and SO2 molecular notation. Need to remember that, if you follow the above-said method, you can construct the SO2 molecular structure very easily.