The size of an atom does not significantly influence whether a photon or graviton is absorbed, as absorption is determined by interactions with charged particles, which are considered point-like. The concept of atomic size is misleading when discussing absorption, as it doesn't correlate with the physical dimensions of larger objects. The atomic mass may affect photon absorption, as more electrons can lead to increased absorption capacity when photons excite electrons to higher energy levels. However, the fundamental interaction remains tied to the nature of the charged particles rather than the atom's size. Overall, the number of electrons in an atom can impact photon absorption, but the relationship is complex and not solely dependent on atomic size.