An element $X$ of group $15$ exists as a diatomic molecule and combines with hydrogen at $773 \, K$ in the presence of a catalyst to form a compound,ammonia,which has a characteristic pungent smell.
$(a)$ Identify the element $X$. How many valence electrons does it have?
$(b)$ Draw the electron dot structure of the diatomic molecule of $X$. What type of bond is formed in it?
$(c)$ Draw the electron dot structure for ammonia and what type of bond is formed in it?

(A) The element $X$ is Nitrogen $(N)$. Its atomic number is $7$,and its electronic configuration is $2, 5$. Therefore,it has $5$ valence electrons.
$(b)$ The diatomic molecule of nitrogen is $N_2$. The electron dot structure shows that each nitrogen atom shares $3$ electrons with the other to complete its octet,resulting in a triple covalent bond.
$(c)$ In ammonia $(NH_3)$,the nitrogen atom shares one electron with each of the $3$ hydrogen atoms. This results in the formation of $3$ single covalent bonds.