What is the definition of atomic mass number?
The mass number (A), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. Because protons and neutrons both are baryons, the mass number A is identical with the baryon number B as of the nucleus as of the whole atom or ion. The mass number is different for each different isotope of a chemical element. This is not the same as the atomic number (Z) which denotes the number of protons in a nucleus, and thus uniquely identifies an element. Hence, the difference between the mass number and the atomic number gives the number of neutrons (N) in a given nucleus: N=A−Z.[1] Good luck!!
Atomic Number: The atomic number of an atom is essentially the number of protons in its nucleus. For example, carbon has 6 protons. Thus, its atomic number is 6. Earlier, we talked about isotopes. Remember that each isotope has the same number of protons? Well, every isotope of an element has the same atomic number. Atomic Mass: The atomic mass of an element is the sum of the number of protons AND neutrons. For example, carbon has six protons. One isotope of carbon also has 6 neutrons. This means that its atomic mass is 12, or 6 protons + 6 neutrons. Another isotope of carbon has 8 neutrons. This means that its atomic mass would be 14, or 6 protons + 8 neutrons.
