Which of the following best describes an ion?

• A. A neutral atom with equal numbers of protons and electrons.
• B. An atom or group of atoms that has a positive or negative charge.
• C. A molecule formed by covalent bonding between atoms.
• D. A substance that cannot be broken down into simpler substances by chemical means.

Answer: (B)

Verified step by step guidance

1. Understand that an ion is a species that carries an electrical charge due to an imbalance between the number of protons and electrons.
2. Recall that a neutral atom has equal numbers of protons (positive charge) and electrons (negative charge), resulting in no net charge.
3. Recognize that when an atom or a group of atoms gains or loses electrons, it becomes charged and is called an ion.
4. Note that ions can be either positively charged (cations) if electrons are lost, or negatively charged (anions) if electrons are gained.
5. Distinguish ions from molecules formed by covalent bonding (which are neutral) and from substances that cannot be broken down further (elements).