Two binary ionic compounds of an unknown metallic element Q are isolated in separate…
CHEMISTRY · Multi-part · AP · Chemistry · Atomic Structure and Properties · Atomic Structure and Properties
Problem
Two binary ionic compounds of an unknown metallic element Q are isolated in separate experiments.
• Compound A has the empirical formula Q3P.
• Compound B has the empirical formula Q2O.
Both compounds are confirmed to be electrically neutral, and neither contains elements other than those shown. The metallic element Q is known to be located in Period 2, Period 3, or Period 4 of the periodic table.
Design a logically sequenced argument that leads to the unique identification of element Q and simultaneously explains the oxidation states exhibited in the two compounds.
(a) Determine the ionic charge of Q in Compound A and the ionic charge of Q in Compound B, showing all reasoning based on charge neutrality.
(b) Using periodic trends in ion formation, narrow the list of candidate elements in Periods 2–4 that can adopt both oxidation states found in part (a).
(c) From the candidates identified in part (b), select the single element that best satisfies the observed stoichiometries, and justify the selection with reference to electronic structure and common chemistry of the element.
(d) Explain why no other element in Periods 2–4 can meet all the constraints simultaneously, citing valence-electron configurations and typical ionic charges for the excluded elements.