Which subatomic particles determine the atomic number of a carbon-12 atom?

• A. Protons
• B. Neutrons
• C. Electrons
• D. Protons and neutrons

Answer: (A)

Verified step by step guidance

1. Recall that the atomic number of an element is defined as the number of protons in the nucleus of an atom.
2. Understand that protons carry a positive charge and uniquely identify the element; for carbon, the atomic number is 6, meaning it has 6 protons.
3. Note that neutrons are neutral particles in the nucleus and contribute to the atomic mass but do not affect the atomic number.
4. Recognize that electrons are negatively charged particles orbiting the nucleus and balance the charge of protons but do not determine the atomic number.
5. Therefore, the subatomic particles that determine the atomic number of a carbon-12 atom are the protons.