Question

Which of the following series of isoelectronic ions correctly lists the ions in order of increasing size (i.e., smallest to largest)?

1) Na+, Mg₂⁺+, Al³⁺+
2) O₂-, F-, Ne
3) Li+, Be2+, B3+
4) N₃-, O₂-, F-

Answer 1

Isoelectronic ions N₃-, O₂-, and F- are listed by increasing size based on their nuclear charge, smallest to largest as F-, O₂-, N₃- respectively.

Step-by-step explanation:

Isoelectronic ions have the same number of electrons but differ in nuclear charge, influencing their size. In this case, N₃-, O₂-, and F- share the same electron count but exhibit varying nuclear charges. The nuclear charge is determined by the number of protons in the nucleus, affecting the electrostatic attraction with electrons. The greater the nuclear charge, the stronger the attraction, pulling electrons closer and resulting in a smaller ionic radius.

Therefore, the order from smallest to largest is F- (9 protons), O₂- (8 protons), and N₃- (7 protons). This sequence reflects the increasing nuclear charge, emphasizing the inverse relationship between nuclear charge and ionic size in isoelectronic ions.