Atoms with the same mass, in the context of the same atomic number or number of protons, typically do not have different masses. The mass of an atom is determined by the combined mass of its protons, neutrons, and electrons.
However, it's important to note that the mass of an individual atom can vary slightly due to the presence of isotopes. Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. Since neutrons contribute to the mass of an atom but not its charge, isotopes of an element have different masses.
For example, carbon-12 and carbon-14 are two isotopes of carbon. Carbon-12 has 6 protons and 6 neutrons, while carbon-14 has 6 protons and 8 neutrons. As a result, carbon-12 has a mass of approximately 12 atomic mass units (amu), while carbon-14 has a mass of approximately 14 amu. These slight differences in mass are due to the differing numbers of neutrons in the atomic nuclei.
In everyday life, the differences in atomic masses between isotopes are typically not significant enough to be noticeable. However, in scientific research and applications such as radiocarbon dating, these slight variations in atomic mass are important for precise measurements and calculations.