Final answer:
The ion formed by each element can be predicted based on their location within the periodic table. Main-group elements tend to form cations with a charge equal to the group number when moving from left to right, and form anions with a negative charge when moving from right to left.
Step-by-step explanation:
The ion formed by each element can be predicted based on their location within the periodic table. When moving from left to right on the periodic table, main-group elements tend to form cations with a charge equal to the group number. For example, group 1 elements like sodium (Na) form 1+ ions, while group 2 elements like calcium (Ca) form 2+ ions. On the other hand, when moving from right to left, elements often form anions with a negative charge.