Question

Elements A,B,C and D have atomic numbers 11,18,1 and 17 respectively. Give the chemical formulae of the compound formed between:

Answer 1

Answer: a ) NaCl

b) No compound.

Explanation:

Atomic number of A is 11 , thus it is sodium. It has electronic configuration of 2,8,1 and thus has 1 valence electron and can form $Na^+$.

Atomic number of B is 18 , thus it is argon. It has electronic configuration of 2,8,8 and thus it is an inert gas.

Atomic number of C is 1 , thus it is hydrogen. It has electronic configuration of 1. It can only share electrons.

Atomic number of D is 17 , thus it is chlorine. It has electronic configuration of 2,8,7 and thus has 7 valence electron and can form $Cl^-$.

a) A and D :

Here Sodium is having an oxidation state of +1 called as $Na^+$ cation and anion is $Cl^-$. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral $NaCl$

b) B and C

As B is an inert gas , it wont combine with C.