The first–ionization energy of O is lower than that of N
CHEMISTRY · Single correct · AP · Chemistry · Atomic Structure and Properties · Atomic Structure and Properties
Problem
The first–ionization energy of O is lower than that of N. Which of the following best explains this deviation from the overall trend within Period 2?
(a) O has a smaller atomic radius than N, so its valence electrons experience a stronger attraction to the nucleus.
(b) O has a greater effective nuclear charge than N, so its 2p electrons are held more tightly.
(c) In O, increased electron–electron repulsion arises when two electrons pair in the same 2p orbital, making the 2p electron easier to remove.
(d) The 2p subshell of O is only half-filled, so it is less stable than the completely filled subshell in N.