Valence electrons Transitional Reasoning Download PDF

Questions

1. 1.

   A student investigates two neutral main-group elements, Element X with ground-state electron configuration $1s^2 2s^2 2p^6 3s^2 3p^4$ and Element Y with $1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^4$. The student hypothesizes that these elements exhibit similar chemical properties because they possess identical numbers of valence electrons. Which statement correctly evaluates this hypothesis by identifying the valence electron count and the specific occupied orbitals for both elements?

   • A) The hypothesis is correct; both elements have 6 valence electrons found in the highest principal energy level ($3s^2 3p^4$ for Element X and $4s^2 4p^4$ for Element Y).
   • B) The hypothesis is incorrect; Element X has 6 valence electrons, whereas Element Y has 16 valence electrons because its filled $3d^{10}$ subshell is also considered valence.
   • C) The hypothesis is correct; both elements have 4 valence electrons because only the electrons in the outermost $p$ subshells act as valence electrons.
   • D) The hypothesis is incorrect; Element X has 4 valence electrons ($3p^4$) and Element Y has 14 valence electrons ($3d^{10} 4p^4$) because filled $s$ subshells are core electrons.