Characteristics of the Hypoiodite Ion

Instructor: Laura Foist

Laura has a Masters of Science in Food Science and Human Nutrition and has taught college Science.

In this lesson we will learn about the hypoiodite ion. We will learn about its structure and how it is formed. We will also learn how it reacts to form iodine and iodates.

Chemical Features of Hypoiodite Ion

Imagine you are in a laboratory creating an antibacterial for dogs. You are directed to create hypoiodite. But you soon realize that this compound is extremely difficult to create.

When mixing water and iodine you simply form hypoiodous acid, with a small amount of hypoiodite ion. It could be a great antibacterial, except that the hypoiodite ion quickly breaks down.

Your boss tells you to explain why you are having difficulties creating this compound, so you look into everything about this unstable ion.

The hypoiodite ion is a molecule with an iodine and an oxygen connected by a covalent bond. It has a negative charge on the oxygen, meaning it has an extra electron. Iodine originally has 7 valence electrons, and oxygen originally has 6 valence electrons.

Since we know there is an extra electron this means there are a total of 14 valence electrons (7 + 6 + 1 = 14). Two of these electrons are participating in the covalent bond. 6 are surrounding iodine and 6 are surrounding oxygen. Since there are only two molecules, it forms a linear compound with a bond angle of 180 degrees. Already we know that the negative charge is going to make it unstable, so it is going to easily react with other compounds.

Each atom ends up with 6 valence electrons, with two electrons shared in the covalent bond.

Making Hypoiodite Ion

The hypoiodite ion is extremely unstable and only occurs in solution. It is made by adding iodine to water and increasing the pH to about 12 (so adding a base such as sodium hydroxide).

In this reaction hypoiodous acid is the main product, but some hypoiodite is formed as well as the conjugate base. We can see in this reaction that the hypoiodite ion has a negative charge and there are hydrogen atoms with a positive charge available. When the hydrogen atom and the hypoiodite ion connect it forms IOH, hypodious acid.

The hypoiodite ion is made by reacting iodine with water

Any of the hypoiodite ion that doesn't turn into hypodious acid quickly undergoes an oxidation reaction to become a mixture of iodides and iodates. Iodides are simply iodine with a negative charge, while iodates are iodine connected to 3 oxygen atoms. This iodate still has a negative charge on the oxygen, but it can be shared between all 3 oxygen atoms through resonance.

Hypoiodite breaks down quickly to form iodides and iodates
Breakdown reaction

Hypoiodite Ion Hybridization

Both the iodine and the oxygen have an sp3 hybridization. This may be confusing at first since there is only one bond, and with sp3 there's supposed to be 4 bonds. But remember the orbitals do not need to be filled with an actual bond, but they can also be filled with lone pairs.

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