Ionic radius Transitional Reasoning Practice

Questions

1. 1.

   A laboratory team investigates three monoatomic ions, $X^{2-}$, $Y^-$, and $Z^{2+}$, each possessing an identical count of 18 electrons. The experimental ionic radii measured for these three species are 99 pm, 181 pm, and 184 pm in an unspecified order. Based on periodic trends and effective nuclear charge, which option correctly pairs each ion with its measured radius and provides the valid scientific justification?

   • A) $X^{2-} = 99\text{ pm}$, $Y^- = 181\text{ pm}$, and $Z^{2+} = 184\text{ pm}$, because cations experience greater electron-electron repulsion than anions with the same electron count.
   • B) $Z^{2+} = 99\text{ pm}$, $Y^- = 181\text{ pm}$, and $X^{2-} = 184\text{ pm}$, because a higher proton-to-electron ratio exerts a stronger inward pull on the identical electron clouds.
   • C) $Z^{2+} = 184\text{ pm}$, $Y^- = 181\text{ pm}$, and $X^{2-} = 99\text{ pm}$, because the addition of protons expands the valence shell via greater nuclear shielding.
   • D) $X^{2-} = 184\text{ pm}$, $Y^- = 99\text{ pm}$, and $Z^{2+} = 181\text{ pm}$, because monovalent ions naturally maintain a smaller ionic boundary than multivalent ions.

Answers and step-by-step solutions appear after you finish the test.