Determine the number of protons and the number of electrons in each ion.
a. Al3+ b. Se2- c. Ga3+ d. Sr2+
Solution : Below is the period table(Table 1) and it has elements highlighted for which the charge is to be predicted and below there is another table(Table 2) that indicates the group and the charges. Table 1 Table 2 Table 2 indicates the charges for the groups in the periodic table. Now, Let’s determine the charges for the elements given: (a) Ga : Ga is the chemical symbol of Gallium. Ga belongs to group 3A. Referring to Table 2, we can predict that Ga has charge of +3. (b) Sr : Sr is the chemical symbol of Strontium. Sr belongs to group 2A and has charge of +2. (c) As : As is the chemical symbol of Arsenic. As belongs to group 5A and has charge of -3. (d) Br : Br is the chemical symbol of Bromine. Br belongs to group 7A and has charge of -1. (e) Se : Se is the chemical symbol of Selenium. Se belongs to group 6A and has charge of -2.