How does the mass number show?

The mass number of an atom is the total count of protons and neutrons in its nucleus. It reflects the atom's isotopic identity and helps distinguish between different isotopes of the same element, which have the same number of protons but different numbers of neutrons. The mass number is typically represented as a superscript to the left of the element's symbol, such as ^AElement, where A is the mass number. It is crucial for understanding atomic stability, nuclear reactions, and the element's behavior in chemical processes.