Question

Selected properties of antimony (Sb) and iodine (I) are listed in the table below.

Element
Atomic radius
(pm)
First ionization energy
(kJ/mol)
Electron affinity
(kJ/mol)
Electronegativity
Sb
145
?
–103
2.05
I
140
1008
–295
?

Which predictions can most likely be made?
Sb has a lower ionization energy but a higher electronegativity than I.
Sb has a higher ionization energy but a lower electronegativity than I.
Sb has a lower ionization energy and a lower electronegativity than I.
Sb has a higher ionization energy and a higher electronegativity than I.

Answer 1

Sb has a lower ionization energy and a lower electronegativity than I.

Reason: Sb and I are in the same period with Sb left of I; across a period ionization energy and electronegativity increase, so Sb should be lower in both. This is supported by the given values (I’s IE = 1008 kJ/mol; Sb’s EN = 2.05 while I’s EA is much more negative at −295 kJ/mol, consistent with I being more electronegative).