Question

Find the oxidation number of $\text{Cl}$ in $$\text{Ca}{\left(\text{Cl}{\text{O}}_{\text{2}}\right)}_{\text{2}}$$.

Answer 1

Hint: Oxidation number is also known as the oxidation state. Oxidation number is the number of the electrons of any atom of an element that the particular atom either gains, loses or shares in order to form a chemical bond with another atom to form the compound or the molecule.
In other words we can say that the oxidation number of an atom is the charge that appears on that atom on forming ionic bonds with other heteroatoms.

Complete step by step solution: So, to get the oxidation of chlorine in the given compound $$\text{Ca}{\left(\text{Cl}{\text{O}}_{\text{2}}\right)}_{\text{2}}$$we will do some calculations as follows,
Let us assume that the oxidation number of the chlorine in the compound =$\text{x}$.
As we know that the values of the calcium atom and the oxygen atom found in the given compound are,
The oxidation number of the oxygen $\text{O}$=$-2$
And the oxidation number of the $\text{Ca}$=$+2$
And for we have already assumed the oxidation number of the chlorine =$\text{x}$
And we know that the total sum of the oxidation numbers of the atoms of a compound should be zero.
So, as per the formula for the given compound $$\text{Ca}{\left(\text{Cl}{\text{O}}_{\text{2}}\right)}_{\text{2}}$$
$+2+2\left(\text{x + 2( - 2)}\right)=0$
$\Rightarrow +2+2\left(\text{x - 4}\right)=0$
$\Rightarrow +2(\text{x - 4)}=-2$
$\Rightarrow (\text{x - 4)}=-1$
$\Rightarrow \text{x}=-1+4$
$\Rightarrow \text{x}=3$
Hence the oxidation number of the $\text{Cl}$ in $$\text{Ca}{\left(\text{Cl}{\text{O}}_{\text{2}}\right)}_{\text{2}}$$is $3$.

Note: Some atoms or molecules or the ions have constant oxidation state or the oxidation number:
1. The overall oxidation state of a neutral atom or molecule is zero, because the net charge on a neutral atom or molecule is zero.
2. The oxidation state of the ions which are charged is equal to the net charge of the ion. For example the oxidation state of all alkali metal ions is always is equal to +1, the oxidation state of all alkaline earth metal ions is always is equal to +2 and that of the boron family is equal to +3.The oxidation state of hydrogen in proton $\text{(}{\text{H}}^{\text{ + }}\text{)}$is +1and in hydride is +1.