Chemistry – Atoms, elements and compounds - Atomic structure and the Periodic Table | e-Consult

Definition: The mass number and nucleon number are terms used synonymously to describe the total number of protons and neutrons present in the nucleus of an atom.

Significance in Atomic Notation: The mass number is represented by the subscript 'A' in the atomic notation of an element (e.g., ²³₁Na). The subscript '1' represents the number of protons (atomic number), and the superscript '23' represents the mass number (number of protons + neutrons).

• Mass Number (A): Represents the total number of nucleons (protons + neutrons).
• Nucleon Number: A synonym for mass number, referring to the total number of protons and neutrons.