CCl3- Lewis structure

CCl₃^– has one carbon atom and three chlorine atoms.

In CCl₃^– Lewis structure, there are three single bonds around the carbon atom, with three chlorine atoms attached to it. Each chlorine atom has three lone pairs, and the carbon atom has one lone pair.

Also, there is a negative (-1) charge on the carbon atom.

Alternative method: Lewis structure of CCl₃^–

Rough sketch

• First, determine the total number of valence electrons

In the periodic table, carbon lies in group 14, and chlorine lies in group 17.

Hence, carbon has four valence electrons and chlorine has seven valence electrons.

Since CCl₃^– has one carbon atom and three chlorine atoms, so…

Valence electrons of one carbon atom = 4 × 1 = 4
Valence electrons of three chlorine atoms = 7 × 3 = 21

Now the CCl₃^– has a negative (-1) charge, so we have to add one more electron.

So the total valence electrons = 4 + 21 + 1 = 26

Learn how to find: Carbon valence electrons and Chlorine valence electrons

• Second, find the total electron pairs

We have a total of 26 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 = 26 ÷ 2 = 13

• Third, determine the central atom

We have to place the least electronegative atom at the center.

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

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

• And finally, draw the rough sketch

Lone pair

Here, we have a total of 13 electron pairs. And three C — Cl bonds are already marked. So we have to only mark the remaining ten 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. And chlorine 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 chlorines.

So for each chlorine, there are three lone pairs, and for carbon, there is one lone pair.

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 – 2 – ½ (6) = -1

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

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

Final structure

The final structure of CCl₃^– features a central carbon atom linked to three chlorine atoms through single covalent bonds. In this arrangement, the carbon atom satisfies the octet rule by forming three bonding pairs and retaining one lone pair, while each chlorine atom fulfills its octet by maintaining three lone pairs of its own. This configuration is the most stable because it results in a formal charge of -1 on the central carbon atom and zero on each chlorine atom, representing the most energetically favorable distribution for the ion. Consequently, this electronic pattern serves as the definitive and most accurate Lewis representation for this anion.

To complete the representation, draw square brackets around the entire Lewis structure and place a “-” or “-1” sign as a superscript outside the upper right bracket. This notation signifies that the negative charge is a property of the whole ion.

Next: NH₂F Lewis structure