Question

Ionization energy is influenced by:

• A. size of an atom
• B. charge on a nucleus
• C. electrons present in the inner shells
• D. None of the above

Answer 1

Answer: (A), (B), (C)

The correct options are
A size of an atom
B charge on a nucleus
C electrons present in the inner shells

$IE$ is influenced by:
(A) Size of an atom: The ionization energy depends upon the size of an atom because with the increase in size, the distance between nucleus and valence electrons increases and hence, the force of attraction between the nucleus and valence electron decreases.
(B) Charge on a nucleus: As the nuclear charge increases, the force of attraction between nucleus and valence electrons increases and hence, it is difficult to remove an electron from the valence shell. Thus, with the increase in nuclear charge, the ionization energy increases.
(C) Electrons present in inner shells: selections are closer to the nucleus than p-electrons, which are closer than d-electrons and these, in turn, are closer than f-electrons of the same principal energy level. Hence, selections experience more attraction from the nucleus than p, d and f electrons. Thus, ionization energy to remove an electron from a given energy level decrease in order $s>p>d>f$.