Answer the following question given this paragraph: An ion is an atom or group of bonded atoms that has a positive or negative charge. Ions are formed when an atom gains or loses electrons from its valence shell ( Figure below ). This process causes an imbalance between the number of positively charged protons and negatively charged electrons, so the overall ion will carry a net positive or negative charge. Q: What is an atom or group of bonded atoms that has a positive or negative charge? A:

Possible answers: I. an photon. II. an electron. III. a neutron. IV. an ion.
The answer is:
IV.