An electron in an atom moves due to the attraction between the negatively charged electron and the positively charged nucleus. The potential energy is between them is negative. The electron has kinetic energy due to its movement around the nucleus. The kinetic energy is positive. The kinetic energy in its initial state is half of the potential energy. In addition, the total electron energy contained within the atom is overall negligible. As the electron moves into higher orbits, its potential energy becomes less positive (as the distance between the nucleus & the electron increases), i.e. the electron’s energy increases. As the electron moves towards higher and higher orbits, its potential energy decreases and eventually reaches zero. The electron becomes free and not bound to an atom when that happens. The electron will be bound to the nucleus as long as it has a negative electron energy. The electron becomes either zero or positive and it is no longer bound to an atom.