Question

How do I determine Loss or gain of electrons for the following elements : Sodium, Nitrogen, Aluminum, Chlorine, Calcium and Oxygen

Answer 1

You have to look in the sign of the charges for each element.

In the case of Sodium, Aluminum, and Calcium you can find them in the following states:

Na⁺, Ca²⁺, Al³⁺.

That positive sign means that those elements, are missing one electron to complete it's electronical configuration. In other words, it means that those elements lost electrons. In the case of Sodium it lost one electron, calcium lost 2 and aluminum 3.

Now, if you have those elements in those states, and then you find them with no charge means that they are gaining electrons:

Na⁺ + 1e^- -------> Na In this case, Sodium gained one electron, that's why it does not posseses charge.

To do this easy, whenever you are passing from the most positive charge to a less positive or more negative charge, it means that you are reducting (gaining electrons) and if are passing from the most negative charge (or less positive charge) to a less negative charge (or most positive charge) you are oxidizing and means that you are losing electrons.

In the case of Nitrogen Chlorine and Oxygen, they can all have negative charge, which means that you have 1, 2, 3 more electrons it's valence shield, meaning that they gained those electrons. And if they are passing to a lower number (a less negative number or most positive number) you are losing those electrons.

Hope this helps.