Mass Number - GCSE Physics Definition

The mass number is the total number of protons and neutrons found in the nucleus of an atom. Protons and neutrons are tiny particles that make up the nucleus, which is the centre of an atom. The mass number helps us understand how heavy an atom is and can be represented by a whole number. For example, if an atom has 6 protons and 6 neutrons, its mass number would be 12. It's important to know the mass number when studying elements and their properties in GCSE Physics, as it helps us differentiate between different isotopes of the same element.