Question

What allows the formation of a positive ion?

Answer 1

The factors that can be defined for the formation of positive ions will be low electronegativity, having less number of valence electrons in its valence shell, etc. Metals form the positive ions.

Complete answer:
We know that there are two types of ions present in any solution, i.e., anion and cation. The positive ion is known as a cation and the negative ion is known as an anion. The factors that can be defined for the formation of positive ions will be low electronegativity, having less number of valence electrons in its valence shell, etc.
When an element has 1, 2, or 3 valence electrons in the valence shell, then these electrons can be removed from the valence shell, and it will form positive ions. The electrons are removed in order to complete its octet to gain stability as having 1, 2 or 3 valence electrons in its valence shells are very unstable. Metals form the positive ions.
For example, the formation of sodium ion, the number of electrons in sodium atom is 11, its electronic configuration is:
$1{{s}^{2}}2{{s}^{2}}2{{p}^{6}}3{{s}^{1}}$
So, the valence shell is 3 and it has one valence electron. When this electron is removed then there is the formation of a positive ion, i.e., sodium cation ($N{{a}^{+}}$).
In the similar way, magnesium ion ($M{{g}^{2+}}$), calcium ion ($C{{a}^{2+}}$), potassium ion (${{K}^{+}}$), etc are formed. These ions are formed because they have very little electronegativity.

Note:
Anions are also formed by the exchange of electrons, i.e., when the electrons are added to the configuration to form the complete octet configuration then we get a negative ion. For example fluoride ion (${{F}^{-}}$), chloride ion ($C{{l}^{-}}$), etc.