Using the periodic table, predict the charges of the ions of the following elements: (a) Ga, (b) Sr, (c) As, (d) Br, (e) Se.

First, find the given elements on the periodic table. The periodic table is organized into periods (horizontal rows) and groups (vertical columns). Elements in the same group generally have the same number of valence electrons, which determine their chemical properties and ion charges. (a) Ga: Gallium is in Group 13 (or 3A) and Period 4. (b) Sr: Strontium is in Group 2 (or 2A) and Period 5. (c) As: Arsenic is in Group 15 (or 5A) and Period 4. (d) Br: Bromine is in Group 17 (or 7A) and Period 4. (e) Se: Selenium is in Group 16 (or 6A) and Period 4.

Next, we can determine the most common ion charge based on the group number of the elements. For elements in Groups 1-2 and 13-18: - Group 1 (or 1A) elements usually form ions with a +1 charge. - Group 2 (or 2A) elements usually form ions with a +2 charge. - Group 13 (or 3A) elements usually form ions with a +3 charge. - Group 14 (or 4A) elements typically do not form ions (e.g., carbon), or may form ions with various charges (e.g., silicon). - Group 15 (or 5A) elements usually form ions with a -3 charge or compounds as covalent structures with no charge. - Group 16 (or 6A) elements usually form ions with a -2 charge. - Group 17 (or 7A) elements usually form ions with a -1 charge. - Group 18 (or 8A) elements are the noble gases which are mostly inert and do not usually form ions.

Based on the group numbers and the common ion charges, we can predict the charges of the given elements. (a) Ga: Gallium is in Group 13, so it usually forms ions with a +3 charge. (b) Sr: Strontium is in Group 2, so it usually forms ions with a +2 charge. (c) As: Arsenic is in Group 15, so it usually forms ions with a -3 charge or form covalent compounds with no charge. (d) Br: Bromine is in Group 17, so it usually forms ions with a -1 charge. (e) Se: Selenium is in Group 16, so it usually forms ions with a -2 charge.