Which subatomic particle can be used to identify an atom as belonging to a specific element?

• A. Electron
• B. Proton
• C. Neutron
• D. Positron

Answer: (B)

Verified step by step guidance

1. Understand that an atom is defined by the number of protons it contains in its nucleus. This number is called the atomic number (Z).
2. Recall that the atomic number uniquely identifies an element because each element has a distinct number of protons.
3. Electrons are negatively charged particles that orbit the nucleus, but their number can vary in ions without changing the element itself.
4. Neutrons are neutral particles in the nucleus that can vary in number, leading to different isotopes of the same element, but they do not change the element's identity.
5. Positrons are not part of the normal atomic structure; they are the antimatter counterparts of electrons and do not define elements.