Which of the following best explains why the second ionization energy of sodium is…
CHEMISTRY · Single correct · A Level · Chemistry · Periodicity and periodic trends · Periodicity and periodic trends
Problem
Which of the following best explains why the second ionization energy of sodium is more than ten times greater than its first ionization energy?
(a) The second electron is removed from the same 3s orbital, but with less electron–electron repulsion it feels a much stronger effective nuclear charge, so far more energy is needed.
(b) Because Na+ already possesses a complete octet, removing another electron disrupts that stable noble-gas arrangement, demanding substantially more energy.
(c) The second electron is removed from a lower principal energy level, so it is much closer to the nucleus and experiences far less shielding by other electrons.
(d) After the first ionization the nucleus effectively becomes more positively charged for the remaining electrons, so the attractive force they feel increases sharply and far more energy is needed.