The First Eight Successive Ionization Energies IE₁, IE₂, …) for Al

Multiple Choice

The first eight successive ionization energies IE₁, IE₂, …) for Al are 578; 1817; 2745; 11,577; 14,842; 18,379; 23,326; and 27,465 kJ/mol.What is the probable explanation for the large jump in energy observed between IE₃ and IE₄?

A) Z_eff decreases as electrons are removed.
B) Electrons in ns and np orbitals are equal in energy.
C) IE₄ reflects that inner-shell electrons with a lower n value are starting to be removed.
D) Aluminum cannot lose four electrons, so IE₄ is meaningless.
E) Electrons with higher angular momentum are harder to remove.