Question

Why do metals form positive ions?

Answer 1

Hint: When an atom loses one or more electrons, it becomes cation that is it has gained positive charge in accordance with the electron that it has lost. On the other hand, if an atom gains one or more electrons it attains negative charge and becomes an anion.

Complete Step by step answer: Cation gains positive charge as when an atom is neutral it has balanced electrons and protons, as it loses one electron, then the number of positive charges becomes more than negative, hence it attains positive charge .
These metals all have valence electrons in an S orbital. These electrons are relatively easy for them to lose and achieve a stable octet of electrons in its outermost energy shell.
Now, metal atoms hold the outer electrons relatively loosely than the inner electrons. Therefore they tend to lose electrons and form cations. Conversely most nonmetals attract electrons as they have more electronegativity and high electron affinity, therefore gain some electrons and for anions.
Examples here include sodium and magnesium ions.
It can be possible to predict whether an atom will form cation or anion based on their position on the periodic table. Alkali earth metals and alkaline earth metals always form cation. These d orbital electrons are easy to lose in different numbers so the atoms can often lose different numbers of these electrons to form differently charged cations. For example iron, silver, nickel, copper etc.

Note: Nonmetals on the other hand lie on the right side of the periodic table. They have too many electrons in the outermost shell, and they need more energy to lose all those electrons to complete their octet. Hence they tend to gain electrons, for example fluorine from fluorine anion.