Sulfur trioxide is a compound with the chemistry formula SO3. This link is of good importance and also studied commonly as that reacts through the water present in the air to produce sulfuric acid.

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When this sulfuric acid, in the gaseous state, mixes with the rain and falls ~ above the Earth, that is dubbed acid rain. The sulfur trioxide is usually colorless and oily however is extremely corrosive in nature.

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

The lewis framework is likewise called one electron dot structure which determines the number of valence electrons current in an atom.

Moreover, they likewise describe exactly how these valence electrons are participating in the bond formation to type a molecule.

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

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


To understand these diagrams, it is crucial to know just how the variety of valence electrons has actually been calculated. The atomic number of the sulfur is 16 which provides its digital configuration 1s2 2s2 2p6 3s2 3p4.

As the p shell requirements to accommodate 6 electrons, there is a need for two much more electrons to complete the 3p shell. On the other hand, the atomic number of oxygen is eight the make its digital 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 attracted in together a manner the 3p and also all 2p shells room filled.

Valence Electrons

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

The organize of the cell nucleus on this electrons is less together with a dearth in number provides these electrons take part in the bond formation.

So, in the instance of sulfur trioxide, six valence electrons in every single atom the sulfur and also three atom of oxygen get involved to form one molecule.

Octet Rule

As every the octet rule, the maximum variety of electrons that can be filled within a valence shell is eight.

When they’re much less than eight electrons, only then one atom undergo a bond development either by accepting 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 electron each.

How Sulfur disobey the octet rule?

The record is in the case of Sulfur which belongs to period 3 that the regular table.

Sulfur can broaden its octet and also can accommodate as much as 12 electrons since of which, the does not follow the octet rule.

Sulfur can do so as it has access to energetic 3d-subshell for bonding.

As there is a little energy difference in between 3p and also 3d shells, through the aid of a tiny excitation, one unpaired electron have the right to move indigenous the 3p shell to the 3d covering easily.


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

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

It is vital to recognize that the sulfur can broaden its octet to combine a preferably of ten to twelve electrons.


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

With this condition, sulfur have the right to now form six covalent bonds allowing twelve electrons approximately its valence shell.

The formation of an ext covalent bonds means the release of more energy, permitting the last configuration to be much more stable.


Lewis structure of SO3

The sulfur trioxide is a tetra atomic chemical molecule wherein both the sulfur and also three oxygen molecule bond through an equal number of valence electrons.

The chart is attracted showing dots the valence electrons roughly the price of both sulfur and oxygen atoms with lines predicting shortcut formation.

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

First, look for the total variety of valence electron in a single sulfur trioxide (SO3) molecule, i beg your pardon is twenty-four.

Next, look for just how many much more valence electrons are required to complete 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 need two valence electrons to stabilize your atom.

Next, look for the number and type of bonds developing within a single sulfur trioxide (SO3) molecule. It is three twin covalent bonds between sulfur and oxygen atom each.

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


Why SO3 forms double bonds?

Because of equal formal charge circulation throughout the atom, twin covalent bonds type in SO3.

It is established by the number of electrons one atom lugged – variety of lone pair of electrons – fifty percent the variety of electrons in link formation.

So, because that oxygen, the is 6-6-1 = -1

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

Now, the formal charge requirements to be neutralized to attain a steady condition, so having +3 at centre and -1 at the end cannot happen. That is the reason why three double covalent bond are created in SO3.

Molecular Geometry of Sulfur Trioxide (SO3)

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

Moreover, through the valence covering electron pair repulsion (VSEPR) theory, the structure of sulfur trioxide (SO3) is found to it is in bent shame or trigonal pyramidal or trigonal planar, where the bond edge is 120°.

As the equal twin bond is formed in 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 reason why the sulfur had actually to increase its octet because that this Lewis framework of SO3.

Therefore, the SO3 molecule transforms out to be non-polar in nature. Examine out the post written top top the polarity that SO3.


The Hybridisation of Sulfur Trioxide (SO3)

The hybridization the SO3 is sp2. That is determined with the help of formula:

Number the hybrid orbitals = number of sigma bond + variety of lone pairs

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

So, the total variety of sigma bonds in a single SO3 molecule is three, and also the total number of lone pairs are 0 (confirm v the Lewis structure).

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

Furthermore, the sp2 hybridization disclosure trigonal symmetry v a bond edge of 120°. Moreover, these three brand-new hybrid orbitals have actually 33.33% attributes of s orbital and also 66.66% characteristics of ns orbital.

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The SO3 belongs to duration 3 the the routine table in which facets tend to broaden their octet and accommodate more than eight valence electrons. The is amazing to recognize that this behavior is not exceptional as most aspects possess this behavior except period two elements. The hybridization in SO3 is sp2 because of the development of one sigma bond and also one pi bond.