The molecular nature of matter is studied through quantum mechanics.
Classical mechanics is the historical precursor of quantum mechanics.
In this theory the state of a system is specified by giving values of
coordinates and velocities.
Classical mechanics accurately describes the motions of objects of large
mass that are moving at speeds much slower than the speed of light.
Classical mechanics ascribes exact trajectories to particles.
The classical wave equation describes the vibrations of strings and light
waves.
The old quantum theory includes Planck’s black-body radiation theory,
Einstein’s theory of the photoelectric effect, and Bohr’s theory of the
hydrogen atom.
The old quantum theories contained quantization as hypotheses.
The old quantum theories have been superseded by quantum mechanics.
