Isotopes - GCSE Physics Definition

Isotopes are different forms of the same chemical element, where each isotope has the same number of protons but a different number of neutrons in the nucleus. This difference in neutron number means isotopes have different mass numbers, although they share the same atomic number because the number of protons remains unchanged. For example, carbon-12 and carbon-14 are isotopes of carbon, with both having 6 protons but differing in their neutron count, at 6 and 8 respectively. Understanding isotopes is important in physics as they can have different properties and applications, including uses in medical imaging and determining the age of archaeological finds through radioactive decay.