Technical Standards and Safety Authority (TSSA) G3 Practice Exam

The atomic number of an element represents the number of what?

1. Electrons

2. Protons

3. Neutrons

4. None of the above

The correct answer is: Protons

The atomic number of an element is defined as the number of protons found in the nucleus of an atom of that element. This is a fundamental property that determines the identity of the element itself. For example, hydrogen has an atomic number of 1, which means it has one proton, while oxygen has an atomic number of 8, indicating it has eight protons. The atomic number is significant because it also determines the number of electrons in a neutral atom, and therefore the chemical properties and reactivity of the element. Each element on the periodic table is unique and organized based on its atomic number, allowing scientists to easily identify and understand various elements and their behaviors in chemical reactions. Other choices, such as neutrons or electrons, do not represent the atomic number, which is explicitly tied to protons.