Effective nuclear charge and shielding Original Scenario-Based Download PDF

Questions

1. 1.

   An exploratory nano-drone navigates the outer electron shells of two neutral Period 3 elements, Element X with atomic number 11 and Element Y with atomic number 17. While hovering in the valence region, the drone's sensors record that a valence electron in Element Y experiences a much stronger net inward electrostatic pull toward the nucleus than a valence electron in Element X. Both elements have identical ten-electron inner cores. Which statement correctly accounts for this observed difference in effective nuclear charge?

   • A) Element Y has significantly fewer core electrons than Element X, which sharply diminishes its overall shielding constant.
   • B) Element Y has a higher nuclear charge than Element X while sharing the same number of core electrons, leading to a much higher effective nuclear charge.
   • C) Valence electrons within Element Y shield one another completely from the nucleus, concentrating the positive charge on a single electron.
   • D) The principal quantum number of the valence shell in Element Y is smaller than in Element X, eliminating core electron shielding entirely.