12.10 The Wave Motion of 12.10 The Wave Motion of Matter & Quantum Matter & Quantum

MechanicsMechanics Since light behaves as waves and Since light behaves as waves and

particles, Louis de Broglie, particles, Louis de Broglie, questioned questioned whether particles whether particles matter behaved as waves.matter behaved as waves.

De Broglie derived an equation that De Broglie derived an equation that describes the wavelength (describes the wavelength (λλ) of a ) of a moving particle:moving particle:

λλ = =

h___mv

12.10 The Wave Motion of 12.10 The Wave Motion of Matter & Quantum Matter & Quantum

MechanicsMechanics De Broglie’s equation predicts that De Broglie’s equation predicts that

all matter exhibits wavelike motions.all matter exhibits wavelike motions. It set the stage for an entirely new It set the stage for an entirely new

method of describing the motions of method of describing the motions of subatomic particles, atoms, and subatomic particles, atoms, and moleculesmolecules

12.10 The Wave Motion of 12.10 The Wave Motion of Matter & Quantum Matter & Quantum

MechanicsMechanics Mechanics (classical and quantum) is Mechanics (classical and quantum) is

the study of the motion of bodiesthe study of the motion of bodies Classical mechanicsClassical mechanics adequately adequately

describes the motions of bodies much describes the motions of bodies much larger than the atoms of which they are larger than the atoms of which they are composed. composed. It appears that such a body It appears that such a body gains or loses energy in any amountgains or loses energy in any amount..

Quantum mechanicsQuantum mechanics describes the describes the motions of subatomic particles and atoms motions of subatomic particles and atoms as waves. as waves. These particles gain or lose These particles gain or lose energy in packages called quantaenergy in packages called quanta..

12.10 The Wave Motion of 12.10 The Wave Motion of Matter & Quantum Matter & Quantum

MechanicsMechanics Another feature of quantum mechanics Another feature of quantum mechanics

that is not present is classical mechanics that is not present is classical mechanics is the uncertainty principle derived by is the uncertainty principle derived by German physicist Werner Heisenberg.German physicist Werner Heisenberg. The The Heisenberg uncertainty principleHeisenberg uncertainty principle

states that it is impossible to know states that it is impossible to know exactly both the velocity and the exactly both the velocity and the position of a particle at the same time.position of a particle at the same time. There is an inverse relationship between knowing There is an inverse relationship between knowing

the position and the velocity of a particle.the position and the velocity of a particle.