# CH3F Lewis structure

CH3F (fluoromethane) has one carbon atom, three hydrogen atoms, and one fluorine atom.

In the CH3F Lewis structure, there are four single bonds around the carbon atom, with three hydrogen atoms and one fluorine atom attached to it, and on the fluorine atom, there are three lone pairs.

Contents

## Steps

Use these steps to correctly draw the CH3F Lewis structure:

#1 First draw a rough sketch
#2 Mark lone pairs on the atoms
#3 Calculate and mark formal charges on the atoms, if required

Let’s discuss each step in more detail.

### #1 First draw a 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 fluorine lies in group 17.

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

Since CH3F has one carbon atom, three hydrogen atoms, and one fluorine atom, so…

Valence electrons of one carbon atom = 4 × 1 = 4
Valence electrons of three hydrogen atoms = 1 × 3 = 3
Valence electrons of one fluorine atom = 7 × 1 = 7

And the total valence electrons = 4 + 3 + 7 = 14

• Second, find the total electron pairs

We have a total of 14 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 = 14 ÷ 2 = 7

• 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 fluorine. Place the least electronegative atom at the center.

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

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

• And finally, draw the rough sketch

### #2 Mark lone pairs on the atoms

Here, we have a total of 7 electron pairs. And four bonds are already marked. So we have to only mark the remaining three electron pairs as lone pairs on the sketch.

Also remember that both (carbon and fluorine) are the period 2 elements, so they can not keep more than 8 electrons in their last shell. And hydrogen is a period 1 element, so it can not keep more than 2 electrons in its last shell.

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

So for fluorine, 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:

### #3 Calculate and mark formal charges on the atoms, if required

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 (8) = 0

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

For fluorine atom, formal charge = 7 – 6 – ½ (2) = 0

Here, the atoms do not have charges, so no need to mark the charges.

In the above structure, you can see that the central atom (carbon) forms an octet. The outside atom (fluorine) also forms an octet, and all hydrogens form a duet. Hence, the octet rule and duet rule are satisfied.

Therefore, this structure is the stable Lewis structure of CH3F.

Next: NH4+ Lewis structure