Which term refers to the total number of protons and neutrons in an atom?

The correct term that refers to the total number of protons and neutrons in an atom is the nucleon number. This term emphasizes that both types of particles reside in the nucleus of the atom and contributes to its mass. The nucleon number provides a way to express the overall mass of an atom from a nuclear perspective.

This term is closely associated with the concept of mass number, which is often used interchangeably. However, the nucleon number specifically highlights the count of all nucleons (protons and neutrons) without indicating mass as a separate entity. It captures the total count that determines an atom's identity and characteristics in nuclear chemistry and physics.

Understanding the distinction between nucleon number and other terms like atomic number or proton number is essential, as those terms refer specifically to the counts of protons or the number of protons that define the element's identity. The mass number, while closely related, typically highlights the total mass aspect rather than the simple count.