What is a positive ion called?

A positive ion is called a cation. This term is used to describe an ion that has lost one or more electrons, resulting in a net positive charge. When atoms, which are typically neutral, lose electrons, they become positively charged because they have more protons (positively charged) than electrons (negatively charged).

Understanding cations is fundamental in chemistry, especially in the context of ionic compounds, where cations typically pair with anions (negative ions) to form neutral compounds. The distinction between cations and anions is crucial for grasping concepts related to chemical bonding, reactions, and the behavior of substances in solution.

The other terms provided refer to different concepts in chemistry: anions are negative ions due to the gain of electrons, protons are positively charged subatomic particles found in the nucleus of an atom, and radicals usually refer to species with unpaired electrons that can participate in chemical reactions. Each of these terms has its own specific context that does not relate to the definition of a positive ion.