Sulfur Dioxide (SO2) Formal Charge

SO2 Formal Charge

In sulfur dioxide (SO2), sulfur (S) has a double covalent bond with one oxygen (O) atom and a single covalent bond with another. SO2 undergoes the following resonance.

O–S+=O ↔ O=S+–O

SO2 Formal Charge

Let us calculate the formal charge of both these structures.

i. O–S+=O

Sulfur

V = 6, N = 2, B = 6

Therefore,

qf = 6 – 2 – 6/2 = 1

Oxygen 1

V = 6, N = 6, B = 2

Therefore,

qf = 6 – 6 – 2/2 = -1

Oxygen 2

V = 6, N = 4, B = 4

Therefore,

qf = 6 – 4 – 4/2 = 0

The net formal charge is: 1 – 1 + 0 = 0

ii. O=S+–O

Sulfur

V = 6, N = 2, B = 6

Therefore,

qf = 6 – 2 – 6/2 = 1

Oxygen 1

V = 6, N = 4, B = 4

Therefore,

qf = 6 – 4 – 4/2 = 0

Oxygen 2

V = 6, N = 6, B = 2

Therefore,

qf = 6 – 6 – 2/2 = -1

The net formal charge is: 1 + 0 – 1 = 0

The formal charge of SO2 is zero. It spends half its time in each of its two resonance structures. It flips back and forth swiftly between the two forms.

By Satyam Bhuyan

Satyam Bhuyan works as a content developer and regularly contributes to sciencefacts.net and chemistrylearner.com. He holds a Ph.D. in Mechanical Engineering and has an in-depth passion for science, especially physics and materials science. When he is not writing, he can be seen in a movie theatre or concert hall. Aside, he is an avid traveler and has lived in six countries.

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