Question

What is the oxidation number of Ca in $C{{a}^{2+}}$ ?

Answer 1

Hint: As we know that the oxidation state of an atom can be described as the hypothetical charge which would be held by that atom if all of its bonds with atoms are completely ionic in nature. So here we have to tell the oxidation state of Ca in $C{{a}^{2+}}$.

Complete answer:
Let us first understand the concept of oxidation state and know about the oxidation as follows:-
-Oxidation state: It can be described as the hypothetical charge which would be held by that atom if all of its bonds with atoms are completely ionic in nature or in simple words we can say that it is the total number of electrons which an atom either gains or losses in order to form a chemical bond with another atom. For a free ion, it is generally written in superscript along with signs.
-Calcium: It is a chemical element (denoted by symbol Ca) and has atomic number 20. Being an alkaline earth metal, it is a reactive element which forms a dark oxide-nitride layer whenever exposed to air. Also its physical and chemical properties are almost similar to its heavier homologues which are strontium and barium.
-As it is an alkaline earth metal, it has 2 electrons in its valence shell which it donates to obtain a noble gas configuration which is $C{{a}^{2+}}$. Here the oxidation state of calcium is +2.
Therefore, the oxidation number of Ca in $C{{a}^{2+}}$ is $+2$.

Note:
-Remember that the concept of oxidation state is very useful in various reactions as well as it helps us to tell the shape of molecules and compounds, therefore you must study and learn how to calculate and use it in different types of questions.