A simple gedanken experiment was proposed that imagines an observer shrinking down and entering the inner space of the atom. This led to five postulates which was justified mathematically using a quantum potential-modified spacetime structure within the atom. The new spacetime structure demonstrated that space was expanded within the atom, time was slowed down and inertial mass was increased. The paper also demonstrated that the uncertainty principle may have its origins in the modification of spacetime within the atom. Application of general relativity to the intraatomic space showed that charge emerges in a natural way from the changes in the spacetime structure. Within the atom, the term 8πG could be replaced with (2(e/m)^2)/ϵ_0 in the gravitational field equation. The absence of nuclear radiations could be attributed to the presence of a black-hole-like horizon around the nucleus, which also could explain the extraordinary stability of the electron within the atom that contains a positively charged nucleus. The spacetime transformation would appear to make the atomic world self-similar to, or symmetric with, the macroscopic world. The product of the space and time intervals in spacetime was invariant, which is in effect a law of conservation of spacetime. Thus, it appeared that spacetime may not be just a field of coordinate points, but a real entity that could be associated with both mass and energy. Inertial mass could be directly related to the proportion of space and time within spacetime.