is: a state of a composite system in which a finite amount of energy is required to separate the components of the system.
is: in Schrödinger's model of the hydrogen atom, a state in which the probability that the electron will escape infinitely far from the proton, is zero.
is: in the Bohr model of the hydrogen atom, any one of an infinite number of possible states, corresponding to the allowed Bohr orbits for the electron, each with its own definite energy corresponding to one of the energy levels. [P8.2, P11.3]
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