Final answer:
An ion has an electrical charge because it has unequal numbers of protons and electrons.
Step-by-step explanation:
An ion has an electrical charge because it has unequal numbers of protons and electrons. An atom is electrically neutral when it has an equal number of protons and electrons. However, when an atom participates in a chemical reaction and gains or loses one or more electrons, it becomes an ion and develops an electrical charge.