What is the total number of protons and neutrons in an atom called?

The total number of protons and neutrons in an atom is referred to as the mass number. This measurement is crucial because it gives an understanding of the atomic composition of an element. Each atom consists of a nucleus that houses protons, which are positively charged, and neutrons, which are neutral. The mass number is the sum of these two particles, reflecting the mass of the nucleus.

In contrast, the atomic mass is a weighted average of the masses of an element's isotopes, and it's measured in atomic mass units (amu). Molecular weight refers to the mass of a molecule, calculated as the sum of the atomic masses of all atoms in a molecule. The atomic number, on the other hand, identifies the number of protons in the nucleus of an atom and determines the element's identity. Understanding the distinctions among these terms is essential for grasping basic atomic structure in the field of chemistry and biology within public health contexts.