Question

Atomic radius(pm) of $Al,Si,N$ and $F$ respectively is:

• A. $117,143,64,74$
• B. $143,117,74,64$
• C. $143,47,64,74$
• D. $64,74,117,143$

Answer 1

Answer: (B)

$143,117,74,64$

Atomic radius(pm) of $Al,Si,N$ and $F$ is $143,117,74,64$ respectively. In a period from left to right atomic radius decreases. Hence, the atomic radius of $F$ is less than the atomic radius of $N$. Also, the atomic radius of $Si$ is less than the atomic radius of $Al$. The atomic radius of $Al$ and $Si$ (third period elements) is higher than the atomic radius of $F$ and $N$ (second period elements). This is because third period elements have an additional shell of electrons than second period elements.