Elements A through D lie consecutively across Period 3 of the periodic table
CHEMISTRY · Multi-part · AP · Chemistry · Atomic Structure and Properties · Atomic Structure and Properties
Problem
Elements A through D lie consecutively across Period 3 of the periodic table. Their atomic numbers increase by one unit from left to right. A forms a white crystalline solid with chlorine that has a 1:1 ionic ratio (empirical formula ACl). B forms a chloride that is used as an antacid. C reacts with chlorine to form a hygroscopic solid whose formula is CCl3. D does not react directly with chlorine under ordinary conditions.
Use these observations, together with periodic-table reasoning, to analyze how valence-electron configuration governs the ionic charge adopted by each element when it forms a binary chloride.
(a) For each element A–D, state the number of valence electrons and identify its periodic-table group.
(b) Predict the most probable ionic charge of each element when it forms a chloride and write the complete chemical formula of that chloride.
(c) Explain why element C forms a trichloride rather than a monochloride, even though both compounds would be electrically neutral.
(d) Element D is often classified as a metalloid. Describe, in terms of effective nuclear charge and energy required to remove electrons, why D is far less likely than A–C to form a simple monatomic ion.