Question

Gradual addition of electronic shells in the noble gases causes a decrease in their:

• A. ionisation energy
• B. atomic radius
• C. boiling point
• D. density

Answer 1

Answer: (A)

ionisation energy

Gradual addition of electronic shells in the noble gases causes a decrease in their ionisation energy. On moving down the group, number of shells and atomic radius increases. Shielding of outer electrons by inner electrons increases. This decreases the force of attraction between outermost electrons and nucleus. Effective nuclear charge and ionisation enthalpy decreases.