Lewis Structure of CH3+

Lewis Structure of CH3+

CH3+ (methenium) has one carbon atom and three hydrogen atoms. In the lewis structure of CH3+, there are three single bonds around the carbon atom, with three hydrogen atoms attached to it, and none of the atoms has a lone pair.

Also, there is a positive (+1) charge on the carbon atom.


Here’s how you can draw the lewis structure of CH3+ step by step.

Step #1: draw sketch
Step #2: mark lone pairs
Step #3: mark charges (if there are)

Let’s break down each step in detail.

#1 Draw Sketch

  • First, determine the total number of valence electrons

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

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

Since CH3+ has one carbon atom and three hydrogen atoms, so…

Valence electrons of one carbon atom = 4 × 1 = 4
Valence electrons of three hydrogen atoms = 1 × 3 = 3

Now the CH3+ has a positive (+1) charge, so we have to subtract one electron.

So the total valence electrons = 4 + 3 – 1 = 6

  • Second, find the total electron pairs

We have a total of 6 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 = 6 ÷ 2 = 3

  • 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.

Hence, here we have to assume that the central atom is carbon.

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

  • And finally, draw the rough sketch
Lewis Structure of CH3+ (Step 1)

#2 Mark Lone Pairs

Here, we have a total of 3 electron pairs. And three C — H bonds are already marked. So we do not have to mark any electron pair as a lone pair on the sketch.

Lewis Structure of CH3+ (Step 2)

#3 Mark Charges

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

Here, the carbon atom has a charge, so mark it on the sketch as follows:

Lewis Structure of CH3+ (Step 3)

In the above structure, you can see that the central atom (carbon) doesn’t form an octet. But in CH3+, carbon has an exception that it does not require eight electrons to form an octet. So no need to worry about the octet rule here.

Therefore, this structure is the most stable lewis structure of CH3+.

And since the CH3+ has a positive (+1) charge, mention that charge on the lewis structure by drawing brackets as follows:

Lewis Structure of CH3+ (Final)

Next: CH2CHCN Lewis Structure

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