Lewis structure of SO

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The Lewis structure of SO contains a double bond between the sulfur atom and the oxygen atom, and both the atoms have two lone pairs.

Steps

By using the following steps, you can easily draw the Lewis structure of SO.

#1 Draw skeleton
#2 Show chemical bond
#3 Mark lone pairs
#4 Complete octet on central atom
#5 Calculate formal charge and check stability

Let’s one by one discuss each step in detail.

#1 Draw skeleton

In this step, first calculate the total number of valence electrons. And then, decide the central atom.

• Let’s calculate the total number of valence electrons

We know that… both sulfur and oxygen are the group 16 elements. Hence, both sulfur and oxygen have six valence electrons.

Now SO has one sulfur atom and one oxygen atom.

So the total number of valence electrons = valence electrons of sulfur atom + valence electrons of oxygen atom

Therefore, the total number of valence electrons = 6 + 6 = 12

• Now decide the central atom

The atom with the least electronegative value is placed at the center. By looking at the periodic table, we get the electronegativity values for sulfur and oxygen as follows:

Electronegativity value of sulfur = 2.58
Electronegativity value of oxygen = 3.44

Obviously, sulfur is less electronegative than oxygen. Hence, assume that sulfur is the central atom.

So now, put sulfur and oxygen next to each other. And draw the rough skeleton structure for the Lewis structure of SO something like this:

Also read: How to draw Lewis structure of CH₂ (4 steps)

#2 Show chemical bond

Place two electrons between the atoms to show a chemical bond as follows:

#3 Mark lone pairs

As calculated earlier, we have a total of 12 valence electrons. And in the above structure, we have already used two valence electrons. Hence, ten valence electrons are remaining.

Two valence electrons represent one lone pair. So ten valence electrons = five lone pairs.

Note that sulfur is period 3 element, so it can keep more than 8 electrons in its last shell. And oxygen is a period 2 element, so it can not keep more than 8 electrons in its last shell.

Also, make sure that you start marking these lone pairs on outside atoms first. And then, on the central atom.

The outside atom is oxygen, so oxygen will get three lone pairs. And the central atom (sulfur) will get two lone pairs.

So the Lewis structure of SO looks something like this:

In the above structure, you can see that the octet is completed on the outside atom. But, the central atom (sulfur) doesn’t form an octet.

So in the next step, we have to complete the octet on the central atom.

Also read: How to draw Lewis structure of AlF₃ (4 steps)

#4 Complete octet on central atom

Remember that sulfur is a period 3 element, so it can keep more than 8 electrons in its last shell.

Now sulfur already has six valence electrons. Hence, sulfur needs two more valence electrons to complete its octet.

So convert one lone pair from the oxygen atom to make a new bond with the sulfur atom. And then, the Lewis structure of SO looks something like this:

In the above structure, you can see that the octet is completed on the central atom (sulfur), and also on the outside atom. Therefore, the octet rule is satisfied.

After completing the octet, one last thing we need to do is, calculate the formal charge and check the stability of the above structure.

Also read: How to draw Lewis structure of Cl (3 steps)

#5 Calculate formal charge and check stability

The following formula is used to calculate the formal charges on atoms:

Formal charge = valence electrons – nonbonding electrons – ½ bonding electrons

Collect the data from the above structure and then, write it down below as follows:

• For sulfur atom

Valence electrons = 6
Nonbonding electrons = 4
Bonding electrons = 4

Formal charge = 6 – 4 – ½ (4) = 0

• For oxygen atom

Valence electrons = 6
Nonbonding electrons = 4
Bonding electrons = 4

Formal charge = 6 – 4 – ½ (4) = 0

Mention the formal charges of atoms on the structure. So the Lewis structure of SO looks something like this:

In the above structure, you can see that the formal charges of both (sulfur and oxygen) are zero. Therefore, this is the stable Lewis structure of SO.

And each horizontal line drawn in the above structure represents a pair of bonding valence electrons.

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Related

• Lewis structure of CH₂
• Lewis structure of AlF₃
• Lewis structure of Cl
• Lewis structure of S₂Cl₂
• Lewis structure of XeF₆

External links

• SO Lewis Structure in 5 Steps (With Images) – Pediabay