# COBr2 Lewis structure

COBr2 (carbonyl bromide) has one carbon atom, one oxygen atom, and two bromine atoms.

In COBr2 Lewis structure, there is one double bond and two single bonds around the carbon atom, with one oxygen atom and two bromine atoms attached to it. Each bromine atom has three lone pairs, and the oxygen atom has two lone pairs.

Contents

## Steps

Here’s how you can easily draw the COBr2 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
#4 Minimize formal charges by converting lone pairs of the atoms, and try to get a stable Lewis structure
#5 Repeat step 4 again if needed, until all charges are minimized

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, carbon lies in group 14, oxygen lies in group 16, and bromine lies in group 17.

Hence, carbon has four valence electrons, oxygen has six valence electrons, and bromine has seven valence electrons.

Since COBr2 has one carbon atom, one oxygen atom, and two bromine atoms, so…

Valence electrons of one carbon atom = 4 × 1 = 4
Valence electrons of one oxygen atom = 6 × 1 = 6
Valence electrons of two bromine atoms = 7 × 2 = 14

And the total valence electrons = 4 + 6 + 14 = 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 carbon is less electronegative than oxygen and bromine, assume that the central atom is carbon.

Therefore, place carbon in the center and oxygen and bromine 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 bonds are already marked. So we have to only mark the remaining nine electron pairs as lone pairs on the sketch.

Also remember that both (carbon and oxygen) are the period 2 elements, so they can not keep more than 8 electrons in their last shell. And bromine 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 oxygen and bromines.

So for oxygen and each bromine, there are three lone pairs, and for carbon, 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 carbon atom, formal charge = 4 – 0 – ½ (6) = +1

For oxygen atom, formal charge = 6 – 6 – ½ (2) = -1

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

Here, both carbon and oxygen atoms have charges, so mark them on the sketch as follows:

The above structure is not a stable Lewis structure because both carbon and oxygen atoms have charges. Therefore, reduce the charges (as below) by converting lone pairs to bonds.

### #4 Minimize formal charges by converting lone pairs of the atoms

Convert a lone pair of the oxygen atom to make a new C — O bond with the carbon atom as follows:

In the above structure, you can see that the central atom (carbon) forms an octet. And the outside atoms (oxygen and bromines) also form an octet. Hence, the octet rule is satisfied.

Also, the above structure is more stable than the previous structures. Therefore, this structure is the stable Lewis structure of COBr2.

Next: GeF4 Lewis structure