The mass of an ion is not necessarily the same as the mass of its parent atom. An ion is formed when an atom gains or loses electrons, resulting in a change in its electrical charge. When an atom loses one or more electrons and becomes positively charged, it forms a cation. Conversely, when an atom gains one or more electrons and becomes negatively charged, it forms an anion.
The mass of an ion depends on the number of electrons gained or lost. Since electrons have a very small mass compared to protons and neutrons, the mass change resulting from electron loss or gain is typically negligible. Therefore, the mass of a cation or anion is often very close to the mass of its parent atom.
However, there are some cases where the mass of an ion can significantly differ from its parent atom. This occurs when isotopes are involved. Isotopes are atoms of the same element that have different numbers of neutrons. If an ion is formed from an isotope of an element, its mass will be different from the mass of the parent atom due to the difference in the number of neutrons.
In summary, while the mass of an ion is usually similar to the mass of its parent atom, there can be cases where the masses differ, especially if isotopes are involved.