Question

Valence shell of element A contains 3 electrons while the valence shell of element B contains 6 electrons. What is the formula of the compound?
A. $A{{B}_{2}}$
B. ${{A}_{2}}B$
C. ${{A}_{2}}{{B}_{3}}$
D. ${{A}_{3}}{{B}_{2}}$

Answer 1

Hint: The outermost shell present in an atom is called valence shell. The valence electrons are going to decide the oxidation state of the particular atom. By using electrons in the valence shell of the atoms we can find the molecular formula of the compounds.

Complete Solution :
- In the question it is given that the valence shell of element A contains 3 electrons while the valence shell of element B contains 6 electrons.
- We have to find the formula of the compound by using the given data.
- By using the given data we can write the electronic configuration of A is $n{{s}^{2}}n{{p}^{1}}$ and electronic configuration of B is $n{{s}^{2}}n{{p}^{4}}$ .
- The element A has 3 electrons in its outermost shell means its valency is 3.
- The element B has 2 electrons in its outermost shell means its valency is 2.
- In the case of element B, in p orbital two electrons are paired and the remaining two electrons are unpaired.
- The unpaired electrons are only involved in bonding and they are called valence electrons.
- Therefore the chemical formed by the elements has a formula of ${{A}_{2}}{{B}_{3}}$ .
So, the correct answer is “Option C”.

Note: The valence electrons of the elements are going to decide the molecular formula of the compound. That too the unpaired valence electrons are only involved in the formation of bonding between the elements.