I BRaVeLY Attempted the Lewis Structure of IBR4- and Survived!

Introduction

Have you ever tried to draw the Lewis structure of a molecule and found yourself completely lost in a sea of lines and electrons? Well, I certainly have! Recently, I was tasked with drawing the Lewis structure of IBR4-, and let me tell you, it was no easy feat. But, using my trusty knowledge of chemistry and a healthy dose of bravery, I managed to conquer the task and come out alive on the other side. So, if you’re ready to join me on this journey, let’s get started!

What is IBR4-?

Before we dive into the complexities of drawing the Lewis structure of IBR4-, let’s take a moment to understand what this molecule actually is. IBR4- is a polyatomic anion that is composed of one iodine atom and four bromine atoms. The negative charge on the molecule indicates that it has gained an electron, making it an anion.

How is IBR4- formed?

IBR4- is formed through a process called oxidation, in which a substance loses electrons. In this case, iodine (I) is oxidized, while bromine (Br) is reduced. The oxidation state of iodine goes from 0 to +1, while the oxidation state of bromine goes from 0 to -1. This reaction can be written as follows:

I + 4Br- → IBR4- + 4e-

The Basics of Drawing Lewis Structures

Now that we understand the basic properties of IBR4-, let’s delve into the process of drawing its Lewis structure. For those of you who may be new to the concept, a Lewis structure is a diagram that shows the connectivity between atoms in a molecule, as well as the placement of electrons.

The Rules of Drawing Lewis Structures

Before we begin drawing, it’s important to understand a few basic rules that must be followed when constructing a Lewis structure:

1. The sum of the valence electrons in a molecule must equal its overall charge.

2. The central atom (in this case, iodine) is typically the least electronegative element, except when it doesn’t make sense.

3. The other atoms in the molecule (in this case, bromine) are attached to the central atom with single bonds.

4. The remaining electrons are placed in pairs around the atoms to fill their valence shells.

Step By Step: Drawing the Lewis Structure of IBR4-

Now that we have a basic understanding of the rules, let’s get started on actually drawing the Lewis structure of IBR4-.

Step 1: Determine the Total Number of Valence Electrons

The first step in drawing a Lewis structure is to determine the total number of valence electrons in the molecule. For IBR4-, we can do this by adding the valence electrons of iodine and bromine and then subtracting 1 electron for the negative charge.

Iodine: 1 x 7 valence electrons = 7 electrons

Bromine: 4 x 7 valence electrons = 28 electrons

Total valence electrons = 7 + 28 – 1 = 34 electrons

Step 2: Determine the Central Atom

The next step is to determine the central atom in the molecule. In IBR4-, iodine is the central atom, as it is the least electronegative element.

Step 3: Connect the Atoms with Single Bonds

The next step is to connect the other atoms to the central atom with single bonds. In IBR4-, there are four bromine atoms, so we connect each of them to the iodine atom with single bonds.

            Br          Br
             |            |
I --- Br --- Br --- Br --- Br

Step 4: Distribute the Remaining Electrons

Finally, we can add the remaining electrons to fill the valence shells of the atoms. For IBR4-, we have 34 valence electrons to distribute.

The iodine atom has 7 valence electrons, so we place 2 pairs of electrons (4 electrons total) around it.

Iodine:

               **
             *    *
            I      *
                  * *

Each bromine atom has 7 valence electrons, so we place 1 pair of electrons (2 electrons total) around each of them.

Bromine:

           *       *
          Br --- Br
           *       *

We have used a total of 32 electrons so far, leaving 2 more electrons to distribute. We add these electrons to the iodine atom, placing one electron in each of its two remaining valence positions.

Iodine:

               **
             *    *
            I    . *
                  * *

And there you have it! The Lewis structure of IBR4- is complete.

Surviving IBR4-: Common Mistakes to Avoid

While drawing the Lewis structure of IBR4- may seem like a daunting task, it’s certainly not impossible. However, there are a few common mistakes that many students make when attempting to draw this molecule that can make the process much more difficult than it needs to be.

Common Mistake #1: Ignoring the Charge

Perhaps the biggest mistake that students make when drawing the Lewis structure of a charged molecule like IBR4- is ignoring the charge altogether. Remember, the charge of the molecule must be taken into account when determining the total number of electrons and how they are distributed.

Common Mistake #2: Forgetting to Connect the Atoms

Another common mistake is forgetting to connect the atoms with single bonds. This step is crucial to the structure of the molecule, and without it, you’ll be left with a disconnected mess of lines and electrons.

Common Mistake #3: Overcomplicating the Diagram

Finally, many students make the mistake of overcomplicating the Lewis diagram. Remember, the Lewis structure is a simplified representation of the molecular structure, and it should be kept as simple as possible.

Conclusion

Drawing the Lewis structure of IBR4- may have been a daunting task, but with a little bravery and a lot of knowledge, it’s definitely possible. By following the basic rules of Lewis structures and avoiding common mistakes, you can conquer even the most complex of molecules. So, take a deep breath, pick up your pencil, and let’s get drawing!

Helpful Table: Valence Electrons of Common Elements

If you’re struggling to determine the number of valence electrons for a specific element, refer to the helpful table below:

References

1. “Lewis Structure.” Wikipedia, Wikimedia Foundation, 31 May 2021, en.wikipedia.org/wiki/Lewis_structure.
2. “IBr4.” PubChem, National Library of Medicine, pubchem.ncbi.nlm.nih.gov/compound/IBr4.