3. Electrons are both a particle AND a waveobservation forces a state Bohr did his work under the assumption they were like particles De Broglie did his work under the assumption they were like waves Heisenberg's Uncertainty Principlethe more you know about the position of the electron, the less you know about its velocity/energy and vice versa. Velocity/energy = wave-like property; position = particle-like property Indeterminacywe can only predict based on probability Schrdinger's Equation: H = Ehelps plot an electron's orbital as probability distribution map. The solutions to the wave functions () are the four quantum numbers