CHEMISTRY · Single correct · AP · Chemistry · Atomic Structure and Properties · Atomic Structure and Properties
Problem
Across Period 3, the first–ionization energy rises overall but dips at both Al and S. Which combination of factors best accounts for these two separate deviations?
(a) Al: pairing of electrons within a 3p orbital increases repulsion; S: electron enters a higher-energy 3p subshell
(b) Both Al and S: larger atomic radii than their preceding elements reduce nuclear attraction on valence electrons
(c) Al: electron enters a higher-energy 3p subshell; S: pairing of electrons within a 3p orbital increases repulsion
(d) Both Al and S: lower effective nuclear charge than neighboring elements reduces attraction on valence electrons