Which of the following best defines an atom?

• A. A molecule composed of two or more different elements bonded together.
• B. A negatively charged particle that orbits the nucleus of an atom.
• C. The smallest unit of an element that retains the chemical properties of that element.
• D. A positively charged particle found in the nucleus of an atom.

Answer: (C)

Verified step by step guidance

1. Understand that an atom is the fundamental unit of matter that defines an element and its chemical properties.
2. Recognize that atoms consist of subatomic particles: protons (positively charged), neutrons (neutral), and electrons (negatively charged).
3. Note that a molecule is a combination of two or more atoms bonded together, which can be of the same or different elements.
4. Identify that the smallest unit of an element that retains the chemical properties of that element is an atom itself, not a molecule or subatomic particle alone.
5. Therefore, the best definition of an atom is: 'The smallest unit of an element that retains the chemical properties of that element.'