Associate Safety Professional Practice Exam

What determines the atomic number of an element?

1. Total number of neutrons

2. Total number of particles

3. Total number of protons

4. Total number of electrons

The correct answer is: Total number of protons

The atomic number of an element is defined as the total number of protons in the nucleus of an atom. This is a fundamental property that not only identifies the element itself but also determines its position in the periodic table. Each element has a unique atomic number, which distinguishes it from all other elements. For example, hydrogen has an atomic number of 1 because it has one proton, while carbon has an atomic number of 6 due to the presence of six protons. The atomic number plays a critical role in defining the chemical properties of an element, as the number of protons affects the number of electrons in a neutral atom, thereby influencing how the element reacts chemically with others.