How are isotopes defined in chemistry?

In chemistry, isotopes are defined as variants of the same chemical element that have the same number of protons but a different number of neutrons. The number of protons in an element determines its atomic number and, thus, identifies the element itself. Since isotopes of a given element have identical proton counts, they share the same chemical properties and position on the periodic table. However, the difference in the number of neutrons results in isotopes having different atomic masses and, in some cases, different stability, leading to radioactivity in certain isotopes. For example, carbon has isotopes like carbon-12 (with 6 neutrons) and carbon-14 (with 8 neutrons), both of which are forms of carbon but differ in mass due to their neutron counts.