Final answer:
A different version of an element with the same number of protons but a different number of neutrons is known as an isotope. Isotopes of an element share the same atomic number but have a varying mass numbers due to different numbers of neutrons.
Step-by-step explanation:
A different version of an element that has the same number of protons but a different number of neutrons is called an isotope. Isotopes have the same atomic number because the number of protons is unchanged; however, the mass number varies as a result of the different numbers of neutrons. For instance, carbon-12 and carbon-14 are both isotopes of carbon, featuring 6 protons but having 6 and 8 neutrons, respectively.
The term radioactive refers to an element or isotope that is unstable and emits radiation. The term parent isotope is used to describe the original atom before it undergoes radioactive decay, while daughter isotope refers to the atom that results from this decay. Therefore, in the context of this question, the correct term to describe a different version of an element with the same number of protons but a different number of neutrons is an isotope.