Question

Find the formal charge of ‘O’ in ozone.

Answer 1

Hint: Generally oxygen from various oxidation states as oxides, superoxides, Peroxides. Oxygen is dioxide and ozone is a type of tri oxygen molecule. Oxygen forms metal oxides with alkali, alkali earth metals, and transition elements.

Complete step by step solution:
The oxygen valence has 6 electrons and electronic configuration is $[He]2s^{2}2p^4$
The molecular formula of ozone = $$O_3$$
Therefore, the valence electrons of ozone = 3X6 = 18 electrons
According to the Lewis electron dot structure of ozone shown below, there are 12 numbers of bonding electrons and 6 numbers of non-bonding electrons.

Formal charge: for establishing and predicting the reactivity of a particular atom in structure with a track of electrons is the importance of formal charge.
The electron count associated with an atom reflects the formal charge on an atom in the molecule when compared to an isolated neutral atom. If the atom has released electrons will be +ve and gained will be –ve.
Formal charges can be calculated by a mathematical formula. The equation compares the number of valence electrons in an isolated atom with the number of valence electrons around the atom in the molecule.
Formal charge =
(Number of valence electrons in the neutral atom) - (number of valence electrons around the atom in the molecule)
Or
Formal charge = valence electrons-(non-bonding electrons)-$${\displaystyle \frac{1}{2}}$$ (bonding electrons)
From the Lewis dot structure,
The formal charge for O (which is represented as 1) = $6-4-{\displaystyle \frac{4}{2}}=0$
The formal charge for O (which is represented as 2) = $6-2-{\displaystyle \frac{6}{2}}=+1$
The formal charge for O (which is represented as 3) = $6-6-{\displaystyle \frac{2}{2}}=-1$

Hence, the formal charge of ‘O’ in ozone is 0, +1, and -1 respectively.

Note: There are methods experimentally to determine the formula charge by a diagrammatic or visual method which is based on the number of valence electrons in an isolated neutral atom and instinctive method which is based on comparing the structure with known neutral structures.