What are isotopes?

Isotopes are defined as atoms of the same element that have the same number of protons but differ in the number of neutrons. This means they share the same atomic number, which identifies them as the same element, but their mass numbers—calculated as the total number of protons and neutrons—will vary due to the differing neutron counts.

For example, carbon has isotopes such as Carbon-12 and Carbon-14. Both isotopes have six protons (giving them the same atomic identity as carbon), but Carbon-12 has six neutrons, while Carbon-14 has eight neutrons. This variance in neutrons can lead to differences in stability and radioactive properties of the isotopes, contributing to their unique behaviors in chemical and physical processes.

The other definitions do not correctly encompass the characteristics of isotopes as established in chemistry. Understanding this concept is fundamental, particularly when exploring nuclear chemistry, radioactivity, and isotope applications in fields such as medicine and archaeology.