How to calculate formal charges of chlorate [ClO3]- ion with lewis structure?
In covalently bonded molecules, formal charge is the charge assigned to an atom based on the assumption that the bonded electrons are equally shared between concerning atoms, regardless of their electronegativity.
The overall formal charge present on a molecule is a measure of its stability.
The fewer the formal charges present on the bonded atoms in a molecule (close to zero), the greater the stability of its Lewis structure.
In this article, we will calculate the formal charges present on the bonded atoms in ClO3– and also the overall charge present on the molecular ion.
How to calculate the formal charges on ClO3– atoms?
The formal charges can be calculated using the formula given below:
The formal charge of an atom = [valence electrons of an atom – non-bonding electrons – ½ (bonding electrons)]
The valence electrons (V.E) of an atom are the total number of electrons present in its valence shell. Valence electrons can be determined by locating the position of the elemental atom in the Periodic Table.
Non-bonding electrons(N.E) are the number of lone pairs present on the atom. (1 lone pair means 2 nonbonding electrons).
Bonding electrons (B.E) are the total electrons shared with the atom via covalent chemical bonds. (1 single bond means 2 bonding electrons).
Now let us use this formula and calculate the formal charges in the most preferred ClO3– structure.
The most preferred Lewis structure of ClO3– is as shown below.
It consists of a total of 26 valence electrons. A chlorine (Cl) atom is present at the center, which is bonded to two atoms of oxygen (O) via double covalent bonds and another oxygen atom via a single covalent bond.
One lone pair of electrons is present at the central Cl-atom. Each of the two double-bonded O-atoms contains 2 lone pairs, while the single-bonded O-atom contains 3 lone pairs, respectively.
It is the best possible Lewis structure of ClO3– because the formal charges are minimized in it, and thus, it is the most stable.
Let’s find out how we can determine the formal charges present on each atom in the above ClO3– Lewis structure.
∴ The formal charge on the Double bonded oxygen (O) atom in ClO3– is 0.
This calculation shows zero formal charges are present on the central Cl atom and two double-bonded O-atoms, while the single-bonded O-atom carries a -1 formal charge, which is also the charge present on the ClO3– ion overall, as shown below.
Finally, the ClO3– Lewis structure is enclosed in square brackets, and a -1 charge is placed at the top right corner.
Vishal Goyal is the founder of Topblogtenz, a comprehensive resource for students seeking guidance and support in their chemistry studies. He holds a degree in B.Tech (Chemical Engineering) and has four years of experience as a chemistry tutor. The team at Topblogtenz includes experts like experienced researchers, professors, and educators, with the goal of making complex subjects like chemistry accessible and understandable for all. A passion for sharing knowledge and a love for chemistry and science drives the team behind the website. Let's connect through LinkedIn: https://www.linkedin.com/in/vishal-goyal-2926a122b/
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