Chemistry
Chemistry
Problem
A chemist writes down the formulas NaCl, CaCl₂, and AlCl₃ while reviewing periodic trends. Using only the information contained in these formulas and your knowledge of atomic structure, analyze the series to reveal how elements that belong to different groups combine with chlorine. Answer all parts thoroughly and support each conclusion with explicit reasoning. a. For each compound, state the charge on the cation that must be present to balance the chloride anions. b. Write the complete systematic (Stock) name of each compound. c. Describe in detail how the observed cation charges are related to (i) the group number of each element on the periodic table and (ii) the number of valence electrons those elements possess. d. Gallium is located directly beneath aluminum in the periodic table. Predict the empirical formula and the systematic name of the binary chloride that gallium would form, and justify your prediction with reference to the trend established in parts (a)–(c).Intuitive explanation
The key insight here is that ionic charge determines stoichiometry—the number of chlorine atoms bonded to each metal reveals how many electrons that metal loses. Sodium loses 1 electron (Na⁺), calcium loses 2 (Ca²⁺), and aluminum loses 3 (Al³⁺), which directly correlates with their position in the periodic table: Group 1, Group 2, and Group 13 respectively. By reading the formulas, you're actually decoding the valence electrons available for bonding, which increases predictably as you move across a period or down a group.
Intuitive explanation
The key insight here is that ionic charge determines stoichiometry—the number of chlorine atoms bonded to each metal reveals how many electrons that metal loses. Sodium loses 1 electron (Na⁺), calcium loses 2 (Ca²⁺), and aluminum loses 3 (Al³⁺), which directly correlates with their position in the periodic table: Group 1, Group 2, and Group 13 respectively. By reading the formulas, you're actually decoding the valence electrons available for bonding, which increases predictably as you move across a period or down a group.