Classification Of Elements And Periodicity In Properties

(i) Atomic Size of Noble Gases:
The atomic size of noble gases is comparatively larger because these gases have completely filled electron shells, which reduces the effective nuclear charge acting on the outermost electrons. The electrons in the outer shell experience less attraction from the nucleus, allowing them to be farther from the nucleus, which increases the atomic radius. Additionally, noble gases have high ionization energies, making it harder for their electrons to be removed, contributing to their larger atomic size.

(ii) Hydrogen Bonding in Nitrogen vs. Chlorine:
Although nitrogen and chlorine have similar electronegativities, nitrogen is able to form hydrogen bonds, whereas chlorine cannot. This is because nitrogen has a smaller atomic size, and its lone pair of electrons is more concentrated, making it highly electronegative and able to form strong hydrogen bonds with hydrogen. Chlorine, on the other hand, is larger, and its lone pair of electrons is more diffuse, making it less effective at forming hydrogen bonds despite having a similar electronegativity.