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Isotopes can be identified by using a value called atomic mass. Atomic mass is the sum of the number of neutrons and the number of protons in a nucleus. The mass can be given in names for isotopes, such as hydrogen-1, hydrogen-2, and hydrogen-3. Carbon, which has an atomic number of 6, has three isotopes: carbon-12, carbon -13, and carbon-14. How many protons are in the nucleus of each isotope? How many neutrons? What is the atomic mass of each of carbon's isotopes?
Students should be able to answer these questions after having created lithium isotopes in class.
Answers: carbon's three isotopes have atomic masses of 12, 13, and 14. All have 6 protons. C-12 has 6 neutrons, C-13 has 7 neutrons, and C-14 has 8 neutrons.