Which statement best describes the difference between an ion and an atom?

• A. An ion is formed by the addition of protons to an atom.
• B. An ion is always larger in size than an atom.
• C. An ion contains more protons than neutrons, while an atom contains equal numbers of protons and neutrons.
• D. An ion has a net electrical charge due to the loss or gain of electrons, while an atom is electrically neutral.

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the definition of an atom. An atom is the smallest unit of an element that retains the chemical properties of that element. It consists of protons, neutrons, and electrons, with the number of protons equal to the number of electrons, making it electrically neutral.
2. Step 2: Understand the definition of an ion. An ion is an atom or molecule that has gained or lost one or more electrons, resulting in a net electrical charge. This means the number of electrons is not equal to the number of protons.
3. Step 3: Recognize that the charge of an ion depends on whether electrons are lost or gained. Losing electrons results in a positively charged ion (cation), while gaining electrons results in a negatively charged ion (anion).
4. Step 4: Analyze the incorrect statements: - Protons are not added or removed to form ions; only electrons are involved. - Ion size can be larger or smaller than the atom depending on the charge, so size is not a definitive difference. - The ratio of protons to neutrons does not define ions or atoms; it defines isotopes.
5. Step 5: Conclude that the best description is that an ion has a net electrical charge due to the loss or gain of electrons, whereas an atom is electrically neutral because it has equal numbers of protons and electrons.