In introductory chemistry, which statement best describes the difference between an atom and an ion?

• A. An atom is always a metal, while an ion is always a nonmetal.
• B. An atom always has more protons than electrons, while an ion always has equal numbers of protons and electrons.
• C. An atom has no net electric charge, while an ion has gained or lost electrons and therefore has a net charge.
• D. An atom is made only of protons and neutrons, while an ion is made only of electrons.

Answer: (C)