# GaCl3 Lewis structure

GaCl3 (gallium trichloride) has one gallium atom and three chlorine atoms.

In GaCl3 Lewis structure, there are three single bonds around the gallium atom, with three chlorine atoms attached to it, and on each chlorine atom, there are three lone pairs.

Contents

## Steps

Here’s how you can easily draw the GaCl3 Lewis structure step by step:

#1 Draw a rough skeleton structure
#2 Mention lone pairs on the atoms
#3 If needed, mention formal charges on the atoms

Now, let’s take a closer look at each step mentioned above.

### #1 Draw a rough skeleton structure

• First, determine the total number of valence electrons

In the periodic table, gallium lies in group 13, and chlorine lies in group 17.

Hence, gallium has three valence electrons and chlorine has seven valence electrons.

Since GaCl3 has one gallium atom and three chlorine atoms, so…

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

And the total valence electrons = 3 + 21 = 24

• Second, find the total electron pairs

We have a total of 24 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 = 24 ÷ 2 = 12

• Third, determine the central atom

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

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

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

• And finally, draw the rough sketch

### #2 Mention lone pairs on the atoms

Here, we have a total of 12 electron pairs. And three Ga — Cl bonds are already marked. So we have to only mark the remaining nine electron pairs as lone pairs on the sketch.

Also remember that gallium is a period 4 element, so it can 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 gallium, there is zero lone pair because all nine electron pairs are over.

Mark the lone pairs on the sketch as follows:

### #3 If needed, mention formal charges on the atoms

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

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

For gallium atom, formal charge = 3 – 0 – ½ (6) = 0

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

Here, both gallium and chlorine atoms do not have charges, so no need to mark the charges.

In the above structure, you can see that the central atom (gallium) doesn’t form an octet. But, gallium 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 stable Lewis structure of GaCl3.

Next: NSF Lewis structure