How to draw SO2 Lewis Structure? - Science Education and Tutorials

Q: What is the SO2 Lewis structure?

SO2 Lewis structure is dot representation

Q: What is the formal charge on the SO2 Lewis structure?

Zero charges on the SO2 molecular structure

The sulfur dioxide chemical formula is SO2. Drawing SO2 Lewis Structure is very easy to by using the following method. Here in this post, we described step by step method to construct SO2 Lewis Structure. The sulfur and oxygen elements come as the member of the same oxygen family groups from the periodic table respectively. The valence electrons in sulfur and oxygen are six. Sulfur dioxide is used as a sulfonating agent for organic synthesis.

Table of Contents

Key Points To Consider When Drawing The SO2 Electron Dot Structure

A three-step approach for drawing the SO2 Lewis structure can be used. The first step is to sketch the Lewis structure of the SO2 molecule, to add valence electrons around the sulfur atom; the second step is to add valence electrons to the two oxygen atoms, and the final step is to combine the step1 and step2 to get the SO2 Lewis Structure.

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

Finally, you must add their bond polarities to compute the strength of the two S-O double bonds (dipole moment properties of the SO2 molecule). The sulfur-oxygen bonds in sulfur dioxide(SO2), for example, are polarised toward the electronegative oxygen atoms in SO2 molecule, and because both bonds have the same size and are located around two oxygen terminals of the V-shaped or bent with one lone pair (in total two electrons) on the central sulfur atom, their sum of dipole moment is nonzero due to the SO2 molecule’s bond dipole moment and greater electron polarity to the oxygen atoms. Because each two S-O bonds polarity not canceled each other in the SO2 molecule due to the V-shaped or bent geometry of the SO2 molecule. The sulfur disulfide(SO2) molecule is classified as a polar molecule.

The molecule of sulfur dioxide (with V-shaped or bent molecular geometry) is tilted, the bond angles between sulfur and oxygen are 119.1 degrees. It has a difference in electronegativity values between sulfur and oxygen atoms, with central sulfur’s pull being less as two-terminal oxygen’s in the SO2 molecule. But they not canceled each other due to the asymmetrical V-shaped or bent structure with one lone pair in the central sulfur atom in the molecular geometry of the SO2 molecule.

As a result, it has the nonzero dipole moment. The SO2 molecule has a nonzero dipole moment due to an unequal charge distribution of negative and positive charges. But both sulfur and oxygen atoms fall on the oxygen family groups in the periodic table respectively. The oxygen atom has a higher electronegative value than sulfur in the SO2 molecule. The SO2 molecule has the net dipole moment of 1.61D value in the ground state energy level.

SO2 molecule has two S-O double bonds. Its dipole moment in the ground state is totally different as compared with the excited state. If it absorbs light may be from visible or UV light. It undergoes pi to pi star and n to pi star transition from ground state energy level to excited state energy level. In the excited state energy level, the SO2 molecule shows a definite dipole moment. But it is very dynamic in nature.

Molecules can be classified as polar or nonpolar. The molecule polar behaves in a different manner as compared to nonpolar.

Overview: SO2 Lewis Structure

The central atom is sulfur, which is bordered on two terminals with oxygen atoms( in V-shaped or bent geometry), and one lone pair on the central sulfur atom in the V-shaped or bent molecular geometry. Sulfur has six outermost valence electrons, indicating that it possesses six electrons in its outermost shell, whereas sulfur has six valence electrons in its outermost shell. To complete the octet of the sulfur atom requires two valence electrons on each of their outermost shell.

Two oxygen atoms establish covalent connections with the central sulfur atom as a result, leaving the sulfur atom with one lone pair. There is one lone pair of electrons on the sulfur central atom that resists the bond pairs of the two S-O bonds. According to VSEPR theory, the single S-O bond pairs polarity leads the SO2 molecule to take on the V-shaped or bent geometry structure.

The SO2 molecule’s two S-O bonds are arranged in asymmetrical polarity order around the V-shaped or bent molecular geometry, giving rise to the SO2 molecular shape. The SO2 molecule has a V-shaped or bent molecular geometry because there is electrical repulsion between the lone pairs of electrons in sulfur and two double bond pairs(S-O) of the SO2 molecule.

Lewis structure of SO2 has dot electron representative structure. Valence electrons of atoms undergo orbitals mixing in the chemical reactions, gives new types of molecular species of SO2. The molecule is nothing but a bundle of valence electrons from the atoms. But it is converted to bond pairs and lone pairs in the molecular structure.

Electronegative value Difference Calculation of SO2 Molecule:

Sulfur and oxygen Electronegative difference in SO2:

The sulfur atom has an electronegativity of 2.58, while oxygen has an electronegativity of 3.44 in the SO2 molecule. The difference in electronegativity of sulfur and oxygen can be estimated using the method below.

The electronegative value difference between sulfur and oxygen in SO2 molecule
Electronegativity value of sulfur = 2.58
Electronegativity value of oxygen= 3.44
Difference of electronegativity value between sulfur and oxygen in SO2 molecule = 3.44 – 2.58 = 0.86
Electronegativity difference between S-O bond calculation of SO2 molecule

The electronegative difference between sulfur and oxygen is greater than 0.5. This indicated the bond polarity moves near to polar nature. S-O bond polarity in the SO2 molecule is polar.

Because of this difference in electronegativity of sulfur and oxygen atoms, the SO2 molecule’s S-O bonds become nonpolar. The total net dipole moment of the SO2 molecule is nonzero due to the noncancellation of the bond dipole moment in the V-shaped geometry due to the presence of one lone pair of electrons in the central sulfur atom. The electronegativity of an atom is the strength with which it may attract bound electron pairs to its side. The polarity of SO2 is discussed in our previous post.

As a result, the S-O bond’s dipole moment is less due to the low polarization of the bonds and one lone pair of electrons on sulfur, and all S-O bonds’ dipoles are arranged in the asymmetrical SO2 molecular geometry. The SO2 molecule has a nonzero net dipole moment.

The electron dot structure of the SO2 molecule is also known as the SO2 Lewis structure. It determines the number of outermost valence electrons as well as the electrons engaged in the SO2 molecule’s bond formation. The outermost valence electrons of the SO2 molecule must be understood while constructing the Lewis structure of the molecule.

The sulfur atom is the middle element in SO2 molecular geometry, with six electrons in its outermost valence electron shell, whereas the oxygen atom has six electrons in its outermost valence electron shell. The oxygen atom has six valence electrons.

The SO2 has a total of 18 valence electrons as a result of the foregoing above-said reasoning. With the core central sulfur atom, the two terminals with two oxygen atoms form covalent bonds, leaving the sulfur atom with one lone pair in the middle of V-shaped or bent molecular geometry.

Because one lone pair on the central sulfur atom create interaction with S-O bond pairs(it makes V-shape in the molecular geometry). The bond angle of the O=S=O bond in the V-shaped or bent molecular geometry is approximately 119 degrees. This angle is greater than the CH4 molecule bond angle. The S-O bond length is 146pm(picometer).

To sketch the SO2 Lewis structure by following these instructions:

Step-1: SO2 Lewis dot Structure by counting valence electrons on the sulfur atom

To calculate the valence electron of each atom in SO2, look for its periodic group from the periodic table. The oxygen group families, which are the 16th in the periodic table, are both made up of sulfur and oxygen atoms. In their outermost shells, oxygen and sulfur have six valence electrons respectively.

Calculate the total number of valence electrons in the SO2 molecule’s outermost valence shell. The first step is to determine how many electrons are in the SO2 Lewis structure’s outermost valence shell. An electron in an atom’s outermost shell is known as a valence electron. It is represented by dots in the SO2 Lewis diagram. The SO2 molecule’s core sulfur atom can be represented as follows:

Total outermost valence shell electron of sulfur atom in SO2= 6
Total outermost valence shell electron of oxygen atom in SO2= 6
The SO2 molecule has one central sulfur and two oxygen atoms. Then the total outermost valence shell electrons can be calculated as follows
∴ Total outermost valence shell electrons available for SO2 Lewis structure( dot structure) = 6+2*6= 18 valence electrons in SO2.
calculation of total valence electron of SO2 molecule

Choose the atom with the least electronegative value atom and insert it in the center of the molecular geometry of SO2. We’ll choose the least electronegative value atom in the SO2 molecule to place in the center of the SO2 Lewis structure diagram in this phase.

But in this case, oxygen is higher electronegative than sulfur. So that sulfur stays in the central molecular structure. The electronegativity value in periodic groups grows from left to right in the periodic table and drops from top to bottom.

The first step is to put six valence electrons around the sulfur atom as given in the figure.

Step-2: Lewis Structure of SO2 for counting valence electrons around the terminal oxygen atoms

As a result, oxygen is the first atom in the periodic table’s oxygen family group. Sulfur is the second member of the oxygen family. It is the second element in the oxygen family on the periodic table. The electronegative value of the oxygen atom is slightly higher than that of the sulfur atom in the SO2 molecule. Furthermore, sulfur has a six-electron limit since it is the less electronegative element in the SO2 molecule.

In the SO2 Lewis structure diagram, the sulfur atom can be the center atom of the molecule. As a result, central sulfur in the SO2 Lewis structure, with all two oxygen atoms arranged in aV-shaped or bent geometry.

Add valence electron around the oxygen atom, as given in the figure.

Step-3: Lewis dot Structure for SO2 generated from step-1 and step-2

Connect the exterior and core central atom of the SO2 molecule with two double S-O bonds. In this stage, use two oxygen atoms on the outside of the SO2 molecule to the central oxygen atom in the middle.

Count how many electrons from the outermost valence shell have been used in the SO2 structure so far. Each S-O double bond carries two electrons because each sulfur atom is connected to two oxygen atoms by two S-O double bonds. Bond pairings of S-O are what they’re called.

So, out of the total of 18 valence electrons available for the SO2 Lewis structure, we used eight electrons for the SO2 molecule’s two S-O double bonds. The SO2 molecule has one lone pair of electrons in the central sulfur atom.

Place the valence electrons in the S-O bond pairs starting with the core sulfur, two oxygen atoms in the SO2 molecule. In the SO2 Lewis structure diagram, we always begin by introducing valence electrons from the central sulfur atom(in step1). As a result, wrap around the central sulfur atom’s bond pair valence electrons first (see figure for step1).

The sulfur atom in the molecule gets only 10 electrons around its molecular structure. This central sulfur atom is extra octet stable. But it has one lone pair. Sulfur compound(S8) is a yellowish solid in nature. when sulfur undergoes sublimation from the solid state to the gaseous state. But Sulfur is a very old anti-biotic for external uses.

Oxygen is a naturally abundant gas on the earth. The source of oxygen in the earth is from plants. During the photosynthetic process, the plant gives oxygen and takes carbon dioxide. It is a very essential gas for life on earth. Planting more trees eradicated the CO2 gas level in the earth.

Sulfur requires 10 electrons in its outermost valence shell to complete the molecular extra octet stability, 8 electrons bond pairs in two S-O double bonds, and one lone pair in the central sulfur atom. One lone pair of electrons on the sulfur atom of the SO2 molecule is placed in a V-shaped or bent geometry. Sulfur already shares 8 electrons to the two S-O double bonds. Then place the valence electron in the oxygen atoms, it placed around six electrons on each atoms(step-2). There are 8 valence electrons placed around two oxygen atoms as lone pair of electrons.

We’ve positioned 8 electrons around the two-terminal oxygen atoms(step-3), which is represented by a dot, in the SO2 molecular structure above. The sulfur atom completes its molecular extra octet stability in the SO2 molecule because it possesses 8 electrons in its (two S-O double bonds) bond pairs with two oxygen in the outermost valence shell.

Count how many outermost valence shell electrons have been used so far using the SO2 Lewis structure. Two electron bond pairs are shown as dots in the SO2 chemical structure, whereas two double bonds each contain eight electrons. The outermost valence shell electrons of the SO2 molecule(bond pairs) are 8 as a result of the calculation. The total valence electron in an oxygen atom is 8.

So far, we’ve used 18 of the SO2 Lewis structure’s total 18 outermost valence shell electrons. One lone pair of electrons on the sulfur atom in the V-shaped or bent geometry of the SO2 molecule.

Complete the middle sulfur atom stability and, if necessary, apply a covalent bond. The central sulfur atom undergoes extra octet stability(due to two double bond pairs of electrons).

The core atom in the SO2 Lewis structure is sulfur, which is bonded to the two oxygen atoms by double bonds (two S-O). With the help of two double bonds, it already shares 8 electrons. As a result, the sulfur follows the extra octet rule and has 8 electrons surrounding it in the middle of the SO2 molecule’s V-shaped geometry.

How to calculate the formal charge on sulfur and oxygen atoms in SO2 Lewis Structure?

Calculating formal charge on the sulfur of SO2 molecule:

The formal charge on the SO2 molecule’s sulfur central atom often corresponds to the actual charge on that sulfur central atom. In the following computation, the formal charge will be calculated on the central sulfur atom of the SO2 Lewis dot structure.

To calculate the formal charge on the central sulfur atom of the SO2 molecule by using the following formula:
The formal charge on the sulfur atom of SO2 molecule= (V. E(S)– L.E(S) – 1/2(B.E))
V.E (S) = Valence electron in a sulfur atom of SO2 molecule
L.E(S) = Lone pairs of an electron in the sulfur atom of the SO2 molecule.
B.E = Bond pair electron in S atom of SO2 molecule
calculation of formal charge on sulfur atom in SO2 molecule

The sulfur core atom (two double bonds connected to two oxygen atoms ) of the SO2 molecule has six valence electrons, one lone pair of electrons(two electrons), and 8 bonding pairing valence electrons. Put these values for the sulfur atom in the formula above.

Formal charge on sulfur atom of SO2 molecule = (6- 2-(8/2)) =0

In the Lewis structure of SO2, the formal charge on the central sulfur atom is zero.

Calculating formal charge on the oxygen of SO2 molecule:

The formal charge on the SO2 molecule’s oxygen terminal atom often corresponds to the actual charge on that oxygen terminal atom. In the following computation, the formal charge will be calculated on the terminal oxygen atom of the SO2 Lewis dot structure.

To calculate the formal charge on the terminal oxygen atom of the SO2 molecule by using the following formula:
The formal charge on the oxygen atom of SO2 molecule= (V. E(O)– L.E(O) – 1/2(B.E))
V.E (O) = Valence electron in a oxygen atom of SO2 molecule
L.E(O) = Lone pairs of an electron in the oxygen atom of the SO2 molecule.
B.E = Bond pair electron in O atom of SO2 molecule
calculation of formal charge on oxygen atom in SO2 molecule

The oxygen terminal atom (one double bond connected to one sulfur atom) of the SO2 molecule has six valence electrons, two lone pairs of electrons(four electrons), and 4 bonding pairing valence electrons. Put these values for the oxygen atom in the formula above.

Formal charge on oxygen atom of SO2 molecule = (6- 4-(4/2)) =0

In the Lewis structure of SO2, the formal charge on the terminal oxygen atom is zero.

Summary:

In this post, we discussed the method to construct the SO2 Lewis structure. First, the valence electrons are placed around the sulfur atom. Second, place the valence electron on the oxygen atoms. Finally, when we combined the first and second steps. It gives SO2 Lewis structure. Need to remember that, if you follow the above-said method, you can construct molecular dot structure very easily.