isotopea variant form of a chemical substance that has the same number of protons but a different number of neutronsCarbon-14 is a radioactive isotope used to determine the age of ancient organic materials.NoteCarbon-14 is a radioactive isotope used to determine the age of ancient organic materials.Elon.io is an online learning platformWe have an entire course teaching TOEFL Academic Vocabulary grammar and vocabulary.Start learning TOEFL Academic Vocabulary now