Chem Explorers

Iodite (IO2-) Ion: Lewis Dot Structure and Molecular Geometry Explained

Iodide is an important compound in chemistry due to its wide variety of applications in the field of medicine, agriculture, and manufacturing. In this article, we will discuss the Lewis Dot Structure and Molecular Geometry of Iodite (IO2-) Ion.

Well go step-by-step through each process and explain in detail whats happening at each stage.

Lewis Dot Structure of Iodite (IO2-) Ion

Valence Electrons Counting:

To start with, we need to count the total number of valence electrons present in the Iodite (IO2-) Ion. Iodine is located in Group VIIA in the Periodic Table and has seven valence electrons, while Oxygen is in Group VIA and has six valence electrons.

Since there are two Oxygen atoms, the total number of valence electrons becomes:

7 + (2 x 6) + 1 = 20

Choosing the Central Atom:

The next step is to choose the central atom for the Iodite (IO2-) Ion. Since Iodine is more electronegative than Oxygen, it will be the central atom.

Connecting the Atoms:

Now we connect the two Oxygen atoms to the Iodine with single covalent bonds. This process gives us the structure:



Completing Octet of Outer Atoms:

The Oxygen atoms have already completed their octet electronic configuration by sharing two valence electrons with Iodine. Since both Oxygen atoms already have the octet electronic configuration, they do not have any lone pairs.

Completing Octet of Central Atom:

The central atom, Iodine, has only shared two pairs of electrons with each Oxygen atom to secure its six valence electrons. Therefore, it has two lone pairs, and we need an additional pair of electrons to complete its octet electronic configuration.

Iodine will obey the expanded octet rule with ten electrons in its outer layer. Formal Charge Calculation:

Now we calculate the formal charge for Iodite (IO2-) Ion.

Formal Charge measures the degree of charge separation in the molecule, with an optimal configuration as neutral with no charge imbalance. The equation for calculating formal charge is as follows:

Formal Charge = Valence Electrons – Non Bonding Electrons – (1/2) Bonding Electrons

Valence electrons for Iodine (Io) = 7;

Non-Bonding Electrons on Iodine atom = 4;

Electrons shared in the two bonds = 4 (Each oxygen shares two covalent bonds with Iodine)

Then, we have

FC = 7 4 4 x 1/2;

= 7 4 2;

= +1

Minimizing Formal Charges and Resonance Structures:

To minimize the formal charge imbalance, we can move one lone pair from an Oxygen atom to the Iodine atom, thereby reducing the formal charge of the Iodine atom to zero and increasing the formal charge of the Oxygen atom with the added lone pair.

This way, we can have two resonance forms for this molecule, which can be represented as follows:



(-1) (+1) 0




(-1) 0 (+1)

From the above resonance structures, we can conclude that the bond between Oxygen and Iodine is a double bond representing pi-bonded electrons that are shared in a molecule.

Molecular Geometry or Shape of Iodite (IO2-) Ion

Overview of Molecular Geometry:

The molecular geometry for Iodite (IO2-) Ion can be predicted using the VSEPR theory. VSEPR is an acronym for Valence Shell electron Pair Repulsion theory, which states that since electrons repel one another, they occupy positions that minimize their repulsion.

In essence, the electron pairs’ geometry within the molecule decides the shape of the molecule. Electron Pair Geometry Calculation:

To calculate the electron pair geometry for the Iodite (IO2-) Ion, we must consider the total pairs of electrons present around the central atom.

In this case, there are three electron pairs, two covalent bonds and two lone pairs, around the central Iodine atom. As a result, the electron pair geometry for the molecule is “trigonal planar.”

Molecular Geometry Calculation:

After the electron pair geometry has been determined, to obtain the molecular geometry, we consider only the bond pairs of electrons since they determine the shape of the molecule.

In this case, there are two bonding regions and two lone pairs, resulting in a molecular geometry of “bent.”

Discussion of Molecular Geometry:

The molecular shape is determined by the position of the atoms forming the covalent bond and the shape of the orbital. Firstly, The trigonal planar electron pair geometry exhibits three equatorial atoms and one axial atom.

The three equatorial atoms bonded to the central Iodine atom produces a downward triangular shape, and the lone pairs rest perpendicular to the equatorial atom plane. On the other hand, the axial atom points oppositely to the Oxygen atoms in the axial plane, with the two remaining lone pairs perpendicular to this plane producing a tetrahedral arrangement.


The Iodite (IO2-) Ion has a molecular geometry shape of “bent”, with a trigonal planar electron pair geometry between the Iodine atom and two Oxygen atoms. Overall, understanding the Lewis Dot Structure and Molecular Geometry becomes useful in chemical science to analyze how atoms form molecules and how these molecules interact with other chemical compounds in the creation of materials used in our everyday lives.

In summary, this article explores the Lewis Dot Structure and Molecular Geometry of Iodite (IO2-) Ion. We covered the steps involved in producing the Lewis Dot Structure and explained the significance of Molecular Geometry in determining the shape of the molecule.

Takeaways from this article include an understanding of valence electrons, the role of electronegativity in choosing the central atom, bond formation, and atom positioning in a molecule. Through this explanation, readers will comprehend the importance of these concepts and how they apply in various scientific disciplines.


1) What is a Lewis Dot Structure? A Lewis Dot Structure is a method used in chemistry to help visualize the electron arrangement in covalent molecules.

2) What is Molecular Geometry? Molecular geometry refers to the spatial arrangement of atoms in a molecule, considering only the bond pairs of electrons.

3) How is Molecular Geometry determined? Molecular Geometry can be determined using the VSEPR theory, which predicts the molecular shape based on the number of electron pairs present.

4) What is the significance of Iodite (IO2-) Ion? Iodite (IO2-) Ion has significant usage in various chemical industries such as medicine and agriculture.

5) How important is the knowledge of Iodite (IO2-) Ion’s structure to scientific research? The knowledge of Iodite (IO2-) Ion’s structure is essential for the advancement of scientific research as it provides insights into how the molecule interacts with other chemical compounds.

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