Which subatomic particle determines the identity of an element?

• A. The number of neutrons in the nucleus
• B. The total mass of the atom
• C. The number of protons in the nucleus
• D. The number of electrons in the atom

Answer: (C)

Verified step by step guidance

1. Understand that the identity of an element is defined by its atomic number, which is the number of protons in the nucleus of an atom.
2. Recall that protons are positively charged particles located in the nucleus, and each element has a unique number of protons.
3. Recognize that neutrons contribute to the mass but do not change the element's identity; different numbers of neutrons create isotopes of the same element.
4. Note that electrons are negatively charged particles orbiting the nucleus and can vary in number without changing the element's identity, affecting only the atom's charge.
5. Therefore, the key subatomic particle that determines the identity of an element is the number of protons in its nucleus.