Question

Using the periodic table, how would you predict the charges of the ions of the following elements?

GA
SR
As
Br
Se

Answer 1

see below

Explanation:

The question is very compless. Ga and Sr are two metals; they have in the last energetic level a number of electrons given from the number of the column of periodic table in which they lay;
then Sr has two electrons that can lose and becomes `Sr^(2+)` while Ga becomes `Ga^(3+)` .

Br an Se are non metals and they try to purchase electrons to complete their octet, becoming anions. Br in the seventh column A (or XVII) has 7 electrons and becomes `Br^-` while Se in the sixth column A(XVI) has 6 electrons and purchasing two electrons becomes `Se(2-)`.

They can also form anions bonding themselves with oxygen `(BrO^-, BrO_2^(-), BrO_3^(-), BrO_4^(-))` giving respectively to oxigen 1,2,3,4 electronic doubles.

Se, with oxygen can also forms `SeO_2^(2-), SeO_3^(2-),`
As is an anphoteric element and can give thre of its 5 electrons as metal (As^3+) or can form anions with oxigen `(AsO_2^(-), AsO_3^(-))` as Br and Se.
I hope to have helped you sufficiently