Which subatomic particle determines the identity of an element?

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

Answer: (B)

Verified step by step guidance

1. Recall 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. Understand that protons carry a positive charge and are unique to each element, meaning no two different elements have the same number of protons.
3. Recognize that neutrons contribute to the atomic mass but do not change the element's identity; isotopes of an element differ in neutron number but are still the same element.
4. Note that electrons determine the atom's charge and chemical behavior but do not define the element itself.
5. Conclude that the subatomic particle that determines the identity of an element is the proton.