Here's why:
* Metals have a tendency to lose electrons because they have relatively low ionization energies. This means it takes less energy to remove an electron from a metal atom compared to a nonmetal atom.
* Nonmetals tend to gain electrons because they have higher electronegativity, meaning they attract electrons more strongly.
When a metal atom loses electrons, it forms a cation, which is a positively charged ion.
Example:
Sodium (Na) is a metal. It has one valence electron, and it readily loses this electron to form a sodium ion (Na⁺).
