Sulfur trioxide is a compound through the chemistry formula SO3. This compound is of great importance and studied widely as that reacts through the water current in the wait to produce sulfuric acid.

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When this sulfuric acid, in the gas state, mixes through the rain and falls ~ above the Earth, that is dubbed acid rain. The sulfur trioxide is generally colorless and oily but is very corrosive in nature.

Also, the is referred to as battery acid and is used to manufacture acids, fertilizers, lead-acid batteries, in the pickling that metal, purification of petroleum, and also others.

The lewis framework is also called an electron dot structure which identify the number of valence electrons existing in an atom.

Moreover, they additionally describe how these valence electrons space participating in the bond formation to type a molecule.

Also, the Lewis structure helps v figuring the end the number and also nature (single, double, and also triple) that the bond displayed with the aid of lines.

This structure is one integral component because that anyone that is beginning to study atomic chemistry.


To recognize these diagrams, it is vital to know exactly how the variety of valence electrons has been calculated. The atomic number of the sulfur is 16 which makes its electronic configuration 1s2 2s2 2p6 3s2 3p4.

As the ns shell needs to accommodate 6 electrons, there is a need for two much more electrons to finish the 3p shell. Top top the various other hand, the atomic number of oxygen is eight that make its electronic configuration 1s2 2s2 2p4.

Again, there is a need for two an ext electrons come stabilize the 2p shell. Now, the Lewis structure demands to be drawn in such a manner that 3p and all 2p shells space filled.

Valence Electrons

The electrons that lie in the outermost shell of an atom that easily takes part in the bond formation are called valence electrons.

The hold of the cell core on these electrons is less along with a dearth in number provides these electrons participate in the link formation.

So, in the case of sulfur trioxide, 6 valence electrons in every single atom the sulfur and three atom of oxygen participate to form one molecule.

Octet Rule

As per the octet rule, the maximum number of electrons that can be filled in ~ a valence covering is eight.

When they’re less than eight electrons, just then one atom undergo a bond development either by agree or donating valence electron to accomplish a stable problem like noble gases.

Both in sulfur and oxygen, over there is a dearth of two valence electrons each.

How Sulfur disobey the octet rule?

The record is in the instance of Sulfur i beg your pardon belongs to duration 3 that the routine table.

Sulfur can expand its octet and can accommodate approximately 12 electrons due to the fact that of which, that does not follow the octet rule.

Sulfur can do so together it has accessibility to energetic 3d-subshell because that bonding.

As there is a tiny energy difference between 3p and also 3d shells, with the help of a little excitation, one unpaired electron can move indigenous the 3p covering to the 3d shell easily.


In instance when all the valence electrons are in the 3s and 3p shell, sulfur can create up to two shared covalent bonds and also two lone pairs.

But, as soon as one valence electron reaches 3d shell, sulfur can produce four shared covalent bonds and also one lone pair.

It is crucial to understand that the sulfur can expand its octet to combine a maximum of ten to twelve electrons.


Moreover, as soon as one more valence electron reaches the 3d shell, the total number of unpaired electron becomes six in the sulfur.

With this condition, sulfur can now form six covalent bonds permitting twelve electrons about its valence shell.

The development of much more covalent bonds way the relax of an ext energy, enabling the final configuration to it is in much more stable.


Lewis structure of SO3

The sulfur trioxide is a tetra atom chemical molecule where both the sulfur and three oxygen molecule bond with an equal number of valence electrons.

The diagram is drawn showing dots the valence electrons roughly the price of both sulfur and oxygen atoms through lines predicting bond formation.

The Lewis framework of sulfur trioxide (SO3) molecule is drawn by:

First, look because that the total number of valence electron in a single sulfur trioxide (SO3) molecule, which is twenty-four.

Next, watch for how many much more valence electrons are needed to finish all the octet in the sulfur trioxide (SO3) molecule.

It is six for a solitary sulfur trioxide (SO3) molecule, wherein both sulfur and each oxygen atom require two valence electrons to stabilize your atom.

Next, look for the number and form of bonds forming within a single sulfur trioxide (SO3) molecule. It is three double covalent bonds in between sulfur and also oxygen atom each.

Lastly, look for the main atom, which will be sulfur in this case. Finally, attract the skeleton as:


Why SO3 forms double bonds?

Because of same formal charge circulation throughout the atom, twin covalent bonds form in SO3.

It is figured out by the variety of electrons one atom lugged – number of lone pair of electrons – fifty percent the number of electrons in bond formation.

So, for oxygen, that is 6-6-1 = -1

And for sulfur, the is 6-0-3 = +3.

Now, the formal charge needs to it is in neutralized to accomplish a stable condition, so having +3 at centre and -1 in ~ the end cannot happen. The is the factor why three double covalent bond are developed in SO3.

Molecular Geometry that Sulfur Trioxide (SO3)

The above image clears that the link angle amongst oxygen-sulfur-oxygen (O-S-O) atoms have to be an ext than 90°.

Moreover, with the valence shell electron pair repulsion (VSEPR) theory, the framework of sulfur trioxide (SO3) is uncovered to be bent shame or trigonal pyramidal or trigonal planar, whereby the bond edge is 120°.

As the equal dual bond is formed between each oxygen and also a sulfur atom and also no lone pair exist on the main atom (sulfur), over there is no distortion in the bond angle what-so-ever.

Moreover, there is equal charge distribution about the sulfur which is the factor why the sulfur had to expand its octet because that this Lewis structure of SO3.

Therefore, the SO3 molecule transforms out to be non-polar in nature. Check out the short article written on the polarity that SO3.


The Hybridisation the Sulfur Trioxide (SO3)

The hybridization that SO3 is sp2. The is established with the aid of formula:

Number of hybrid orbitals = number of sigma bonds + variety of lone pairs

In a single shared dual covalent bond, there exists one sigma (σ) bond and one pi (π) bond.

So, the total variety of sigma bond in a solitary SO3 molecule is three, and also the total variety of lone pairs room 0 (confirm through the Lewis structure).

So, variety of hybrid orbitals are 3 + 0 = 3. That is in sp2 hybridization whereby one s orbital, and also two ns orbitals the the exact same shell within an atom overlaps and also mixes to develop three brand-new hybrid orbitals of similar energy.

Furthermore, the sp2 hybridization promotes trigonal symmetry v a bond angle of 120°. Moreover, these three new hybrid orbitals have 33.33% attributes of s orbital and 66.66% qualities of p orbital.

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The SO3 belong to period 3 of the periodic table in which aspects tend to increase their octet and accommodate an ext than eight valence electrons. The is amazing to recognize that this behavior is not exceptional as most facets possess this actions except period two elements. The hybridization in SO3 is sp2 since of the development of one sigma bond and one pi bond.