When an atom becomes an ion, does its mass number change?
Answer (2)
Its mass number does not change because the atom is losing or gaining electrons, so the change is almost not measurable because the electrons weigh so little.
In other words: its mass number does not change
The mass number of an atom does not change when it becomes an ion. This is because the change only involves electrons, which have a negligible mass compared to protons and neutrons. Therefore, the total number of protons and neutrons—defining mass number—remains constant during this process.
;
