Is SO3 Polar or Non-Polar?

The polarity of molecules is something that we all have questions about, and we also wonder how polarity is determined in molecules. You may find out more about the polarity of SO3 in this article (sulfur trioxide). If you’re curious about the polarity or nonpolarity of SO3, make sure you read through to the conclusion of this article.

Polar or nonpolar is the best way to describe SO3. This is due to the trigonal planar form of sulphur trioxide, which is nonpolar. The electronegativity difference between sulphur and oxygen causes the S-O bond to become polar, but the fact that the three S-O bonds are arranged at a 120-degree angle to one another cancels out the total polarity, resulting in SO3 as a nonpolar molecule..

Sulfur Trioxide (SO3) is planar in shape. Sulfur is sandwiched between three Oxygen atoms, creating a triangular structure.

Oxygen has an atomic number of 8, which means that it has six electrons in its empty shell. Sulfur has an atomic number of 16 and an empty shell with 6 electrons, just like Sulfur.

According to the lewis structure of SO3, we notice that three oxygen atoms are scattered around the single sulphur atom, which is why they resist each other.

Thus, we discovered a SO3 trigonal planer molecule (Sulfur trioxide). The Sulfur atom is the centre of symmetry for all of the oxygen atoms.

And why is Sulphur in the centre of the diagram?

All the atoms in a molecule share the same electronegativity, so the atom with the lowest electronegativity is always at the centre and likely to form the most bonds.

As a result, Sulphur occupies the central position in SO3.

Sulfur, the least electronegative atom in SO3, takes on this role as the central atom.

Non-Polarity is the reason why SO3 exists.

The three Sulfur atoms in the SO3 molecule form a double bond with the one pair of all three Oxygen atoms surrounding the Sulfur atom after their first bonding.

Sulfur and Oxygen atoms form a trigonal planar geometric structure because of the three bonds that connect them. The three bonds formed have a 120-degree angle to one another.

As oxygen has a higher electronegativity of 3.44, and sulphur has a lower electronegativity of 2.58, the Sulfur-Oxygen bond is polar.

However, because the three bonds are at an angle of 120 degrees to one another, the SO3 molecule’s overall polarity is nullified.

The nonpolar character of SO3 can be seen in the form of the molecule. Any molecule’s polarity can be determined in part by its chemical structure.

Some additional parameters, such as the number of lone pairs and the molecule’s dipole moment, are also taken into account when determining whether a molecule is either polar or not.

Sulfur trioxide (SO3) has a wide range of molecular species and crystalline forms in which it can be found.

Due to the fact that Sulfur is in the +6 oxidation state, SO3 is an extremely powerful oxidising agent.

It’s colourless and odourless while it’s a liquid, and crystals form when it’s a solid.

When it’s in its gaseous state, it works as a pollutant, like acid rain. Humans and aquatic life alike are at risk from acid rain, which is rain laced with Sulfur trioxide (SO3).

How can you tell the polarity of something?

There are numerous chemical dimensions that reveal the molecule’s composition, geometric structure, dipole moment, and bond formation.

Dimensions like these can also be used to determine the molecule’s polarity.

The dipole moment of SO3 is 0 D, which is vital to know. The debye unit of dipole moment in the SI is designated by the letter ‘D’.

This signifies that the molecule is nonpolar if its dipole moment is equal to zero.

Because it is nonpolar, the molecule has an equal distribution of charge.

There are two types of molecules: those that have no net dipole moment, and those that have net dipole moments because of the nature of their polarity.

Molecule of oxygen in the atmosphere Nonpolar molecules, such as O2, serve as an example. In addition, the SO2 with a bent shape has a net dipole moment, making it polar.

For more information on the polarity of SO2, see our other article.

Bond length charge on each element is multiplied by the molecule’s dipole moment to get the total charge on each element

In addition to the dipole moment, the molecule’s geometrical shape also plays a role in determining its polarity.

Because of its form, sulphur trioxide (SO3) has no polarity because of its trigonal planar structure.

Sulfur trioxide’s bond formation illustrates its symmetry, which renders it nonpolar.

Check out this article on the SO3 Lewis Structure and its Molecular Geometry for more information.

The polar and nonpolar molecular types.

Whenever bonding between two atoms happens, one atom shares the electron of the other and vice versa.

In nonpolar molecules, the atoms involved in the molecule share an equal distribution of charge however, in polar molecules, the atoms do not share equal distribution of charge.

In certain nonpolar circumstances, the electrons shared by both atoms in a covalent connection shifts towards the atom with a greater amount of electronegativity.

And the atom with smaller electronegativity permits its bound electron to migrate towards the other atom with higher electronegativity.

Basically, the electronegativity of an atom is the measure of how strongly an atom can pull the electron towards its own side.

So, in polar instances, due to variances in electronegativity values, the linked electrons are not in between both the atoms due to which polarity develops in the molecule.

The dipole moment of a polar molecule comes out to be a positive value. However, the dipole moment of nonpolar molecules is zero Debye.

Each S-O bond’s dipole moment cancels out, just like in SO3.

Ans: Polar or nonpolar is SO3

Because of the following characteristics, SO3 is a nonpolar molecule:

Although Sulfur and Oxygen atoms in the S-O link in the SO3 molecule have the same electronegativities, the electronegativities of these two elements differ. However, the electronegativity difference is cancelled out by the symmetrical geometry.

A trigonal planar with Sulfur as the centre atom and the oxygen atoms surrounding it at an angle of 120 degrees each is the geometrical shape of the SO3.

The net dipole moment is 0 because of the symmetry of the bond and the trigonal planar form of the molecule. S-O bonds have a dipole moment, although the net dipole moment is zero.

I hope that I’ve answered all of your questions on the polarity of SO3 (sulfur trioxide molecule). Post your questions and I’ll get back to you as soon as possible in the comment box below.

Read more: Diagram of the H3O+ Lewis structure and geometry as well as hybridization

Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.


Please enter your comment!
Please enter your name here

Read More