How to calculate formal charges of hypochlorite (ClO)- 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 the hypochlorite [ClO]– ion and also the overall charge present on it.
How to calculate the formal charges on ClO– 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 calculated 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 to calculate the formal charges in the most preferred Lewis structure of [ClO]–.
The most preferred Lewis representation of the hypochlorite [ClO]– ion is as shown below.
It consists of a total of 14 valence electrons. The molecular ion comprises only two atoms; one chlorine (Cl) atom to which one oxygen (O) atom is bonded via a single covalent bond.
Three lone pairs of electrons are present on the Cl-atom and also on the O-atom.
It is the best possible Lewis structure of ClO– 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 ClO– Lewis structure.
Formal charge on the Chlorine atom = 7 – 6 – 2/2 = 7 – 6 – 1 = 7 – 7 = 0
∴ The formal charge on the Cl-atom inClO– is 0.
This calculation shows that zero formal charges are present on the Cl-atom, while on O-atom, a -1 formal charge is present, which is also the formal charge present on the ClO– ion overall, as shown below.
As a final step, the ClO– Lewis structure is enclosed in square brackets, and a -1 formal charge is placed at the top right corner.
The formal charges present on the bonded atoms in ClO– can be calculated using the formula given below:
V.E – N.E – B.E/2
Where –
⇒ V.E = valence electrons of an atom
⇒ N.E = non-bonding electrons, i.e., lone pairs
⇒ B.E = bonding electrons
What is the formal charge on Cl-atom inClO–?
The chlorine (Cl) atom carries zero formal charges in ClO–.
What is the formal charge on the O-atom in ClO–?
-1 formal charge is present on the oxygen (O) atom in ClO–.
How many lone pairs and bond pairs are present on the oxygen atom in ClO–?
The oxygen (O) atom contains 3 lone pairs and 1 bond pair of electrons in ClO–.
How many lone pairs and bond pairs are present on the chlorine atom in the ClO– Lewis structure?
In ClO–, the chlorine (Cl) atom also contains 3 lone pairs and 1 bond pair of electrons.
What is the overall formal charge on ClO–?
The overall formal charge on ClO– is -1.
Summary
The best possible Lewis structure of a molecule or molecular ion is the one in which the bonded atoms carry formal charges as close to zero as possible.
The formal charge formula is [ V.E – N.E – B.E/2].
In ClO–, zero formal charges are present on the Cl-atom.
The O-atom has a -1 formal charge in ClO–.
The overall formal charge on the hypochlorite [ClO]– ion is -1.
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/
Topblogtenz is a website dedicated to providing informative and engaging content related to the field of chemistry and science. We aim to make complex subjects, like chemistry, approachable and enjoyable for everyone.
