The size of an atom does not significantly affect its mass. The mass of an atom is determined primarily by the total number of protons and neutrons in its nucleus. The electrons, which orbit the nucleus in energy levels or electron shells, have a very small mass compared to protons and neutrons.
The protons and neutrons have relatively equal masses, and their combined mass accounts for most of the atomic mass. Electrons, on the other hand, have a much smaller mass. The mass of an electron is approximately 1/1836 times the mass of a proton or neutron. Therefore, the mass of electrons is typically considered negligible when calculating the overall atomic mass.
While the size of an atom is determined by the arrangement and distribution of its electrons, it does not significantly contribute to the overall mass of the atom. Instead, the atomic mass is primarily influenced by the number of protons and neutrons in the nucleus.