CH2S Lewis structure

CH₂S (thioformaldehyde) has one carbon atom, two hydrogen atoms, and one sulfur atom.

In CH₂S Lewis structure, there is one double bond and two single bonds around the carbon atom, with one sulfur atom and two hydrogen atoms attached to it. And on the sulfur atom, there are two lone pairs.

Alternative method: Lewis structure of CH₂S

Rough sketch

• First, determine the total number of valence electrons

In the periodic table, carbon lies in group 14, hydrogen lies in group 1, and sulfur lies in group 16.

Hence, carbon has four valence electrons, hydrogen has one valence electron, and sulfur has six valence electrons.

Since CH₂S has one carbon atom, two hydrogen atoms, and one sulfur atom, so…

Valence electrons of one carbon atom = 4 × 1 = 4
Valence electrons of two hydrogen atoms = 1 × 2 = 2
Valence electrons of one sulfur atom = 6 × 1 = 6

And the total valence electrons = 4 + 2 + 6 = 12

Learn how to find: Carbon valence electrons, Hydrogen valence electrons, and Sulfur valence electrons

• Second, find the total electron pairs

We have a total of 12 valence electrons. And when we divide this value by two, we get the value of total electron pairs.

Total electron pairs = total valence electrons ÷ 2

So the total electron pairs = 12 ÷ 2 = 6

• Third, determine the central atom

Here hydrogen can not be the central atom. Because the central atom is bonded with at least two other atoms, and hydrogen has only one electron in its last shell, so it can not make more than one bond.

Now we have to choose the central atom from carbon and sulfur. Place the least electronegative atom at the center.

Since carbon is less electronegative than sulfur, assume that the central atom is carbon.

Therefore, place carbon in the center and hydrogen and sulfur on either side.

• And finally, draw the rough sketch

Lone pair

Here, we have a total of 6 electron pairs. And three bonds are already marked. So we have to only mark the remaining three electron pairs as lone pairs on the sketch.

Also remember that carbon is a period 2 element, so it can not keep more than 8 electrons in its last shell. Hydrogen is a period 1 element, so it can not keep more than 2 electrons in its last shell. And sulfur is a period 3 element, so it can keep more than 8 electrons in its last shell.

Always start to mark the lone pairs from outside atoms. Here, the outside atoms are hydrogens and sulfur. But no need to mark on hydrogen, because each hydrogen has already two electrons.

So for sulfur, there are three lone pairs, and for carbon, there is zero lone pair because all three electron pairs are over.

Mark the lone pairs on the sketch as follows:

Formal charge

Use the following formula to calculate the formal charges on atoms:

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

For carbon atom, formal charge = 4 – 0 – ½ (6) = +1

For each hydrogen atom, formal charge = 1 – 0 – ½ (2) = 0

For sulfur atom, formal charge = 6 – 6 – ½ (2) = -1

Here, both carbon and sulfur atoms have charges, so mark them on the sketch as follows:

The above structure is not a stable Lewis structure because both carbon and sulfur atoms have charges. Therefore, reduce the charges (as below) by converting lone pairs to bonds.

Convert a lone pair of the sulfur atom to make a new C — S bond with the carbon atom as follows:

Final structure

The final structure of CH₂S comprises a central carbon atom connected to a sulfur atom by a double covalent bond and to two hydrogen atoms by single covalent bonds. In this configuration, the carbon atom satisfies the octet rule by forming four total bonds (two with sulfur and one with each hydrogen). Within this layout, the sulfur atom fulfills its octet by maintaining two lone pairs alongside its double bond, while the hydrogen atoms reach their stable duet state. This arrangement represents the most stable state for the molecule because it results in a formal charge of zero for every atom, including the carbon, sulfur, and both hydrogens. Therefore, this specific electronic distribution serves as the definitive and most accurate Lewis representation of thioformaldehyde.

Next: C₄H₈ Lewis structure

External video

• How to Draw the Lewis Structure for CH2S – YouTube • Wayne Breslyn

External links

• https://lambdageeks.com/ch2s-lewis-structure/
• https://homework.study.com/explanation/draw-the-lewis-structure-for-ch2s-and-provide-the-following-information-a-name-b-total-number-of-valence-electrons-c-electron-pair-geometry-d-molecular-geometry-e-polarity.html
• https://www.chegg.com/homework-help/questions-and-answers/two-posssible-lewis-structures-molecule-ch2s-given-determine-formal-charge-atom-structures-q32017086
• https://www.quora.com/How-is-the-Lewis-structure-for-CH2S-determined
• https://www.numerade.com/ask/question/5-draw-lewis-structures-for-ch2s-one-where-carbon-is-central-and-one-where-s-is-central-evaluate-formal-charge-on-each-atom-in-each-structure-which-structure-is-more-stable-and-why-6-draw-le-80896/