Ionic radius Transitional Reasoning Download PDF

Questions

1. 1.

   A student investigates three ions, $X^{2-}$, $Y^-$, and $Z^{2+}$, which all possess the identical noble gas electron configuration of argon ($18\text{ e}^-$). Upon measuring their ionic radii, the student records values showing that radius decreases in the order $X^{2-} > Y^- > Z^{2+}$. Which statement correctly accounts for this observed sequence in ionic size?

   • A) The number of occupied principal energy levels decreases from $X^{2-}$ to $Z^{2+}$, causing the valence electrons in $Z^{2+}$ to occupy a shell closer to the nucleus.
   • B) The effective nuclear charge decreases as atomic number increases, allowing the outer electron cloud of $Z^{2+}$ to expand more than that of $X^{2-}$.
   • C) The increasing number of protons from $X^{2-}$ to $Z^{2+}$ exerts a stronger electrostatic attraction on the identical number of electrons, drawing the electron cloud inward.
   • D) Anions inherently occupy an additional electron shell compared to cations formed from the same period, guaranteeing a larger ionic radius regardless of nuclear charge.