SO2 Lewis Structure

SO2 lewis structure is a bent structure with an O–S–O bond angle of 119°. A single sulfur atom and two oxygen atoms are found in this compound.

SO2 Lewis Structure

:eight_pointed_black_star: Sulfur Dioxide (SO2) Lewis Structure

There are two oxygen atoms and one sulfur atom in each molecule of sulfur dioxide. Lewis structure of SO2 will be built using VSEPR theory and consideration of the stability of intermediate structures by these guidelines.

  • It is a colorless, odorless, and very deadly gas, Sulfur dioxide. When dissolved in water, it forms a diluted acid solution that may be used for many purposes. In autos and industrial plants, the burning of petroleum fuel results in the production of this gas. Sulfur atoms and oxygen atoms in SO molecules form two double bonds.

  • The eight valence electrons on Sulfur must be arranged in the Lewis structure before SO2 may be considered a Lewis molecule. The formal charge of every atom must also be calculated to create the optimum Lewis structure.

  • You already know that Sulphur and Oxygen both have six valence electrons. Two Oxygen atoms mean a total of 18 valence electrons in this system.

Depending on the form, geometry, and lone pairs of SO2, there exist a variety of Lewis structures. All four of these gases’ SO2 Lewis structures have the same shape: they’re all bent. Two sigma bonds may be found in hydrogen sulfide, water, sulfur dioxide, and nitrogen dioxide. Finally, both Ozone and SO2 contain a single pair of electrons on their core atoms.

For Sulphur:

  • No. of valance electron = 6

  • Lone pairs = 2

  • No. of bonds = 2

  • So, FC = 6-2-(2×2) = 0

For Oxygen:

  • No. of valence electrons = 6

  • Lone pairs = 2

  • No of bonds = 2

  • So, Formal Charge (FC) = No. of valence electrons – No. of Bonds – 2 X (Lone pairs) = 0

The hybridization of atoms may be determined once the Lewis structure of SO2 has been obtained. Even though it’s a helpful chemical, this substance is poisonous and hazardous to humans.


When Sulfur Dioxide is breathed, it causes a negative response. Respiratory infections can cause coughing and mucus secretion, which can develop into more serious conditions such as chronic bronchitis or asthma.

:eight_pointed_black_star: Making Of SO2’s Lewis Structure

Making of SO2

1. Determine The Total Number Of Electrons In The Valence Shells.

The two molecules located on this compound are members of the VIA elements, and as a result, they have six valence electrons. Multiply the number of atoms found on each molecule by the number of valence electrons found on each molecule, and then add the results.

  • Valence electrons from 2 oxygen atoms = 6 * 2 = 12

  • Valence electrons from 1 sulfur atom = 1 * 6 = 6

  • Total valence electrons = 12 + 6 = 18

2. Calculate The Total Number Of Electron Pairs In The System.

Once you’ve determined the number of electron pairs, you may divide the total number of valence electrons by two to get the total number of valence electrons. You have a total of six.

SO2 total electron pairs /2= 12/2= 9

3. Atom Selection In The Center

When determining which atom should serve as the center atom, the atom with the greatest valence will be taken into consideration. In the case of SO2, sulfur possesses the greater valence of the two atoms. You will witness the bond order, the single bond form, and the double bond form in action.

4. Mark Lone Pairs On Atoms

There are two of them in the S-O bond. When marking a lone pair, count the number of pairs that are remaining. Take the valence electrons on the exterior of the oxygen atom, which should display two bonds, and work your way inward.

It is expected that there will be six valence electron pairs from Oxygen atoms, leaving one valence electron pair remaining. That will be noted as a lone pair under the Sulfur atom in the periodic table.

5. Examine The Stability Of The Atoms

When determining which structure is the most stable, it is necessary to determine the charges of the atoms in the most basic form that they can be found. The charges of each atom will be easier to designate because the lone pair has already been identified, as have those that are bound. It will employ the following formula:

Formal Charge = No. of valence electrons – No. of Bonds – 2 X (No. of lone pairs) = 6-2-(4) = 0


There is a single sulfur pair and two single oxygen pairs in the SO2 Lewis structure. The sp2 hybridization is present in all atoms. In addition to the lone pair and one sigma bond, each oxygen atom possesses two more single electron pairs as well. It is possible to create hybridization with sulfur by using two bonds (sigma bonds) and one lone pair (lone pairs).

:eight_pointed_black_star: Implementation Of The VSEPR Theory

The Lewis structure of SO2 is drawn using the procedures outlined below. The following sections go into further depth about each phase. If you are a newbie to the lewis structure drawing, take your time and read through each part carefully to ensure that you grasp everything.

  • The total number of electrons in the valance shells of the sulfur and oxygen atoms should be determined.

  • The total number of electron pairs

  • The choosing of the center atom

  • Put lone pairs on the atoms to make them more stable.

  • To test for stability and to reduce the amount of charge on atoms in a structure, convert lone pairs to bonds until the most stable structure is produced.

:eight_pointed_black_star: About Sulfur Dioxide (SO2)

:small_red_triangle_down: Fast Facts

Element Sulfur dioxide
Chemical formula SO2
Molar mass 64.066 g mol−1
Appearance Colorless gas
Point group C2v
Coordination geometry Digonal
Molecular shape Dihedral
Dipole moment 1.62 D
Odor Pungent; similar to a just-struck match
Density 2.6288 kg m−3
Melting point −72 °C
Boiling point −10 °C
Solubility in water 94 g/L, forms sulfurous acid
Vapor pressure 237.2 kPa

Sulfur dioxide (IUPAC spelling) is the chemical compound with the formula SO2. It’s a poisonous gas that gives a burnt match scent. It is naturally emitted by volcanoes and is a by-product of heavy metals removal and sulfur-bearing fossil fuel combustion. Sulfur dioxide has a nitric acid scent.

Sulfur dioxide is used to make sulfuric acid. In 1979, the US utilized 23.6 million metric tonnes (26,014,547 US short tonnes) of sulfur dioxide for this purpose, whereas other uses required 150 thousand metric tonnes (165,347 US short tonnes). Sulfur dioxide is mostly created by sulfur combustion. Roasting pyrite and other sulfide ores in the air also produces sulfur dioxide.

Metal sulfur dioxide complexes are formed when sulfur dioxide binds to metal ions in oxidation states 0 or 1. The ligand is usually monodentate, linked to the metal through sulfur, which might be planar or pyramidal.

:small_red_triangle_down: SO2 Lewis Structure Resonance

SO2 has a C2v symmetry point group. Using only s and p orbitals, valence bond theory describes the bonding as a resonance between two resonance structures.

Sulfur dioxide is present in modest proportions on Earth and the atmosphere at around 1 ppm. Sulfur dioxide is found in varying amounts on several planets, with Venus having the highest concentration at 150 ppm.


One-SO2 (S-bonded planar) ligands operate as Lewis bases utilizing the S lone pair. SO2 is a Lewis acid in its 1:1 adducts with Lewis bases such as dimethylacetamide and trimethylamine. SO2 has EA = 0.51 and EA = 1.56 when bonding to Lewis bases.

:eight_pointed_black_star: Properties Of SO2

SO2 Properties

An illustration of the Lewis Structure. Sulfur Dioxide’s Lewis Structure will first necessitate that you obtain the total valence electrons on both Sulfur and Oxygen. Sulfur’s outermost shell should now include everything.

As long as there are lone or nonbonding pairs of electrons in either Sulfur or Oxygen’s six valence electron configurations, it can gain or lose atoms and share them until all six are utilized.

  • Electron Geometry: SO2 has a trigonal planar electron shape. This isn’t like molecular geometry, where the only thing taken into account while determining the form is the total number of atoms. All electron pairs, including lone electron pairs, are included in electron geometry. Electrons in a bonding pair are oriented at a 120-degree angle in SO2.

  • Polarity: Sulfur Dioxide is polar because of an electrostatic charge imbalance across other atoms in the molecule. Because sulfur, being the least electronegative element, draws the molecule’s charge to one side while accumulating a partial negative charge, SO2 is a polar molecule.

  • Bond Angle: Bond angles in SO2 are 120°, according to the molecular geometry. In other words, the o-orbitals are SP2 orbitals in a very close approximation. Even though there are several bonds, including double bonds and one or more triple bonds, the bond angles are the same on all of them.

  • Hybridization: Oxygen atoms have one sigma bond and two lone pairs in Sulfur Dioxide, much as Sulfur atoms. As a result, SP2 is the hybridization of SO2. After you sketch the skeletal structure of the molecule and show how the sulfur and oxygen atoms form a double bond, you will clearly understand the transition and explanation.

  • Molecular Geometry: Molecular Geometry can be better understood if you understand how Sulfur and Oxygen’s electrons are dispersed. Oxygen uses four of the six electrons on the outer level of a sulfur atom for each bond. That means there are 10 electrons in five pairs, totaling a total of ten. The Bent or V shape is formed when two double bonds form as a single unit, leaving just one pair.

  • Molar Mass: Assuming that you know the formula n=N/NA (then N=n*NA), you can compute molar mass using it. Avogadro’s constant is 6,0231023, and N is the number of atoms. The molar mass of SO2 is therefore calculated to be 64.066 g/mol.


SO2 combines with water to generate sulfuric acid clouds, which is part of the global sulfur cycle and causes global warming. In the lower atmosphere, concentrations have been estimated to reach as high as 100 ppm, albeit it is only found in trace levels.

:eight_pointed_black_star: Uses Of SO2

SO2 Uses

:small_red_triangle_down: The Precursor To Sulfuric Acid

A sulfur dioxide intermediary in the manufacturing of sulfuric acid, it is changed to sulfur trioxide and then to oleum, which is subsequently turned to sulfuric acid. Sulfur dioxide is used as a catalyst in the synthesis of sulfuric acid.

:small_red_triangle_down: As A Refrigerant

As a result of its ability to condense quickly and its high heat of evaporation, sulfur dioxide is a prospective material for use as refrigerants. The use of sulfur dioxide as a refrigerant in household freezers was common before the invention of chlorofluorocarbons.

:small_red_triangle_down: The Manipulation Of The Climate

In the field of climate engineering, it has been proposed to inject sulfur dioxide into the stratosphere. The cooling effect would be comparable to what was witnessed following the enormous explosive eruption of Mount Pinatubo in 1991, which caused widespread devastation. However, the effects of this type of geoengineering on rainfall patterns would be difficult to predict at the regional level, particularly in monsoon zones.

:small_red_triangle_down: As A Solvent In The Laboratory

Sulfur dioxide is an excellent inert solvent for dissolving highly oxidizing salts, such as sulfuric acid and sulfuric acid. The sulfonyl group is also utilized rarely in chemical synthesis as a source of this compound. Aryl diazonium salts can be converted into aryl sulfonic acid by treating them with sulfur dioxide and cuprous chloride.


Sulfur dioxide is created when sulfur reacts with oxygen and is used for this purpose. It is referred to as the contact process when it comes to turning sulfur dioxide into sulfuric acid. Every year, many billion kg of material is manufactured for this purpose.

:eight_pointed_black_star: Difference Between SO2 And SO3

When comparing sulfur dioxide (SO2) and sulfur trioxide (SO3), the primary difference between the two is the number of oxygen atoms linked to sulfur in SO2. Sulfur dioxide is SO2, while sulfur trioxide is SO3.

  • Both are sulfur oxides. In terms of color, SO2 is a colorless gas at room temperature, whereas SO3 is a colorless to white crystallized solid. Sulfur dioxide’s +4 oxidation state and sulfur trioxide’s +6 oxidation state are the main differences between the two compounds.

  • Unlike sulfur trioxide, which is nonpolar because it lacks an electron pair, sulfur dioxide is polar because of the existence of a single electron pair. So2 and SO3 are shown in the following infographic. There are two elements in sulfur dioxide: sulfur and oxygen atoms. This gaseous molecule is known as SO2. -71°C and -10°C are the corresponding meltings and boiling points.

  • So3, or sulfur trioxide, is a chemical compound composed of one sulfur atom and three oxygen atoms. It is solid at room temperature. The melting point is 16.9°C and the boiling point is 45°C.

  • There are no more electrons on the sulfur atom after three double bonds with oxygen atoms, as in sulfur dioxide. The SO3 molecule exhibits trigonal planar geometry as a result of this. Because of its trigonal planar shape and the absence of a lone electron pair, SO3 is nonpolar.

  • Sulfur atoms and oxygen atoms combine to generate SO2 and SO3 inorganic chemical compounds. Sulfur dioxide is abbreviated as SO2, whereas sulfur trioxide is designated as SO3.

This is a kind of gaseous compound Their chemical and physical characteristics differ greatly. These chemicals are known as sulfur oxides because they are generated when sulfur and oxygen react. When comparing sulfur dioxide (SO2) and sulfur trioxide (SO3), the primary difference between the two is the number of oxygen atoms linked to sulfur in SO2.


sulfur dioxide (SO2) and sulfur trioxide (SO3) are chemical compounds. Both are sulfur oxides. In contrast to SO2 and SO3, which are both colorless gases at ambient temperature, SO3 is a colorless to white crystalline solid.

:eight_pointed_black_star: SO2 Lewis Structure

SO2 Molecular Geometry

The molecular structure is formed by adopting the shape that minimizes the repulsions of electronic couples. The molecular geometry of SO2 and that of carbon dioxide are identical (CO2). The bonding of SO2 will be demonstrated below without any presuppositions.

O === S === O

Sulfur and oxygen share electrons, hence determining the molecular structure of SO2 requires an understanding of the locations and numbers of electrons in each of these two elements’ orbitals.

One electron from each of the six electrons in Sulphur and the four electrons in Oxygen is utilized to form a connection. Because of this, each pair has an equal amount of electrons (ten).

Four pairs are required to form bonds, therefore one pair is left alone. Using two pairs of each, the two double bonds combine into a single unit. We may infer that the molecular form of SO2 is V-Shaped or Bent based on the fact that the solitary alone pair is not included in the shape description.

There are many ways to think about the form of atoms and molecules, but one of the most important is to think about electron geometry. In contrast, just the atoms are taken into account in molecular geometry. When there is only one lone pair, both geometries of any compound are the same.


As a result, our initial impression of the original structure differs significantly from reality. However, SO2 has a trigonal planar electron shape. You must be perplexed by this strange new phrase.

:eight_pointed_black_star: SO2 Hybridization

Sp2 is SO2’s hybridization. There are two ways to look at SO2 hybridization now: theoretically, and practically, by applying the formula. First, you should study the theory, and then you’ll be ready for the formal.

To give you a head start, when one s orbital joins two p orbitals, you have a hybrid state called Sp2 that has three equivalent orbitals. The ground state electrical configuration is similar to that of SO2 in this situation. One electron from the 3px orbital transfers to the 3d orbital when the atom is excited. 3p3 is the result.

It now forms Sp2 hybridization with three analogous orbitals comprising two paired electrons and two unpaired electrons. Sulfur requires the two unpaired electrons from the Sp2 hybridized orbitals to establish two sigma bonds with oxygen atoms.

The second and third pairs constitute the lone pair of sulfur. What about the two electrons of 3p that were not engaged in the hybridization? Sulfur and oxygen’s bonds were produced by two electrons (one in the 3p orbital and the other in the 3d orbital).

:eight_pointed_black_star: Safety Considerations About SO2

SO2 Safety

After the 2018 lower Puna eruption, volunteers with the US Geological Survey tested for sulfur dioxide levels.

  • Inhalation: As a result of the combustion of sulfur-containing fuels such as coal, matches, and coal smoke, people are often exposed to high levels of sulfur dioxide. It is possible to be poisoned by sulfur dioxide in large doses. Exposure to low quantities might also be dangerous over time. Sulfur dioxide exposure has been linked to preterm delivery, according to a comprehensive analysis published in 2011.

  • Regulations in the United States: This level was cut to 0.25 parts per million by the American Conference of Governmental Industrial Hygienists (ACGIH) in 2008. (ppm). A time-weighted average PEL of 5 ppm (13 mg/m3) has been established by OSHA in the United States. In the United States, NIOSH established the IDLH at 100 ppm.

  • Ingestion: However, certain asthmatic people may be sensitive to sulfur dioxide and sodium bisulfite, two food preservatives listed as safe for human consumption by the US-based Center for Science in the Public Interest.

If you are not allergic to sulfites, you may experience symptoms such as dermatitis (itching), urticaria (flooding), hypotension (low blood pressure), gastrointestinal discomfort and diarrhea, and even anaphylaxis.

The Environmental Protection Agency (EPA) was established in 2010 “A new one-hour threshold of 75 parts per billion was established for the principal SO2 NAAQS (ppb). The EPA removed the two current main standards because they would not offer further public health protection given a one-hour standard of 75 ppb.”


After only a few minutes of exposure, those who are hypersensitive to sulfiting agents like sulfur dioxide begin to experience life-threatening symptoms, such as problems breathing.

Frequently Asked Questions - FAQs

People asked many questions about SO2. We discussed a few of them below:

:one: Is SO2 polar or nonpolar?

Even though both molecules have polar bonds, carbon dioxide is nonpolar whereas sulfur dioxide is.

:two: Why does the SO2 have a bent geometry?

The electron pairs that make up the bonds between the terminal atoms will be repelled by them. The center sulfur atom in sulfur dioxide contains just one non-bonding pair, whereas the central oxygen atom in water has two. As a result, water has a lower “H-O-H” bond angle than sulfur dioxide.

:three: Is SO2 dangerous to human health?

Toxic effects on the human respiratory system can be exacerbated by short-term exposure to SO2. Asthmatics and children, in particular, are particularly vulnerable to the effects of SO2.

:four: What is ph3’s trigonal pyramidal structure called?

The Lewis structure of phosphine (PH3) has three sigma bonds and one lone pair surrounding the phosphorous atom. The PH3 structure is trigonal pyramidal in shape. Tetrahedral molecular geometry surrounds the phosphorous atom. The phosphorous atom has four valence electron pairs.

:five: What is SO2 used for?

In a wide variety of industries, sulfur dioxide is employed. Paper and food preservatives are among the many products made using them. Sulfur dioxide poisoning can affect a wide range of workers, including In industries where it is produced as a byproduct, such as smelting copper or power plants, factory employees may be exposed to it.

:six: Is sulfur dioxide cancerous?

Is it possible that sulfur dioxide might cause cancer? The International Agency for Research on Cancer (IARC) found that it is not known if sulfur dioxide causes cancer and hence assessed it as not being classifiable because of the absence of human evidence and the limited data in animals.

:seven: Is SO2 trigonal flat or bent?

Trigonal planar electron-domain geometry is seen in sulfur dioxide, SO2. Sulfur’s 6 valence electrons form two single bonds with two oxygen atoms, while sulfur has one non-bonding lone pair. This is because sulfur has three electron domains.

:eight: Is there a scientific explanation for why the SO2 molecule has a V-shape?

A bent or V-shaped molecular geometry is commonly referred to as SO2 molecular geometry. When it comes to sulfur dioxide, the electron geometry is trigonal planar. The three pairs of electrons that make up the bond are arranged at an angle of 119o.

:nine: Is sulfur a metal?

Non-metallic, tasteless, and odorless sulfur is a multivalent non-metal that is widespread. Sulfur is a yellow crystallized solid in its natural state. Sulfur can be found in its elemental form or the mineral forms of sulfide and sulfate.

:keycap_ten: Is the structure of SO2 linear?

There are two bond pairs and one lone pair of electrons in the SO2 molecule. Although its bond angle reduces from 120° to 119.5° owing to the lone pair’s repulsion, the CO2 molecule has linear geometry since it contains no lone electron pair.

:closed_book: Conclusion

There is a lot of information here on SO2’s atomic and molecular structure and polarity (Sulfur Dioxide). Understanding and sketching the Lewis Structure, like other compounds, can help you completely comprehend how the molecular geometry, characteristics, and other components came to be. to be.

Because sulfur has a greater valence than oxygen, the center atom in the SO2 Lewis Structure is sulfur. Following the dissection of Sulfur and Oxygen linkages, the SO2 Lewis Structure gives the best explanation for how sulfuric acid(1) became such. This substance can be harmful to your health, but it can also be beneficial if you utilize it correctly.

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