The atomic mass A is defined as?

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Multiple Choice

The atomic mass A is defined as?

The mass number A is the total number of nucleons in the nucleus. It counts all protons and neutrons, because these are the particles that contribute most to the nucleus’s mass. Since electrons have far less mass and lie outside the nucleus, they don’t affect A. So A equals the number of protons plus the number of neutrons (A = Z + N). That’s why the description describing the total number of protons and neutrons best fits A. A would only be the count of protons, B refers to electrons, and C describes the total positive charge rather than mass, so they don’t define A. In practice, the atomic mass in amu is close to A, but A is defined strictly as Z plus N.

The mass number A is the total number of nucleons in the nucleus. It counts all protons and neutrons, because these are the particles that contribute most to the nucleus’s mass. Since electrons have far less mass and lie outside the nucleus, they don’t affect A. So A equals the number of protons plus the number of neutrons (A = Z + N). That’s why the description describing the total number of protons and neutrons best fits A. A would only be the count of protons, B refers to electrons, and C describes the total positive charge rather than mass, so they don’t define A. In practice, the atomic mass in amu is close to A, but A is defined strictly as Z plus N.

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