Final answer:
An atom with more electrons than protons is a negatively charged ion, also known as an anion. Atoms such as these are ions, not neutral atoms or isotopes, though isotopes are atoms with differing numbers of neutrons.
Step-by-step explanation:
When an atom has fewer neutrons than protons, it is still concerning the same element, but it is considered an isotope, which is the term for atoms that vary in the number of neutrons within their nuclei (answer to Review Question 1: b. Isotopes). In the case of the main question, an atom that has more electrons than protons is an atom that has gained additional electrons. Because electrons have a negative charge, when an atom has more electrons than protons, it becomes a negatively charged particle, known as an anion. This means the atom is, by definition, a negatively charged ion (answer: b) Negatively charged ion). Atoms become ions when they lose or gain electrons, changing their overall electrical charge. The difference in the amount of charge of an atom is calculated by the formula: Atomic charge = number of protons - number of electrons. Hence, positively charged atoms, called cations, result from the loss of electrons, while negatively charged atoms, called anions, result from the gain of electrons.