Lewis structure of Cl-

Cl^– (chloride) has one chlorine atom.

In the Lewis structure of Cl^–, there are four lone pairs on the chlorine atom. Also, there is a negative (-1) charge on the chlorine atom.

Alternative method: Cl^– Lewis structure

Rough sketch

• First, determine the total number of valence electrons

In the periodic table, chlorine lies in group 17. Hence, chlorine has seven valence electrons.

Since Cl^– has one chlorine atom, so…

Valence electrons of one chlorine atom = 7 × 1 = 7

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

So the total valence electrons = 7 + 1 = 8

Learn how to find: Chlorine valence electrons

• Second, find the total electron pairs

We have a total of 8 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 = 8 ÷ 2 = 4

• Third, determine the central atom

There is only one atom present here, so assume that the central atom is chlorine.

• And finally, draw the rough sketch

Lone pair

Here, we have a total of 4 electron pairs. So we have to mark these four electron pairs as lone pairs on the sketch.

Also remember that 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. But here, there is no outside atom. So for chlorine, there are four lone pairs.

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 chlorine atom, formal charge = 7 – 8 – ½ (0) = -1

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

Final structure

The final structure of Cl^– consists of a single chlorine atom that has achieved a stable octet by gaining one additional electron. In this arrangement, the chlorine atom satisfies the octet rule by possessing four lone pairs in its valence shell, mimicking the electronic configuration of the noble gas argon. Within this layout, the atom reaches its most stable state as a negatively charged ion. Accordingly, this specific electronic distribution serves as the definitive and most accurate Lewis representation of the chloride ion.

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: C₅H₁₂ Lewis structure

External video

• How to Draw the Lewis Dot Structure for Cl- (Chloride ion) – YouTube • Wayne Breslyn