Wave Mechanics and Orbitals

The quantum theory provided many improvements in the understanding of different electron energy states within an atom.

HOWEVER, some questions were still left unanswered. What is the electron (e-) doing in the atom? Where does the electron spend its time inside the

atom?

Louis de Broglie (1923):

Louis de Broglie (1923):Einstein theorized that light is both a wave

and a particle (ex. a photon)De Broglie used Plank’s and Einstein’s

theories to postulate that if a wave could behave like a particle, then a particle could behave like a wave.

De Broglie’s theory was that “electrons have a wave nature”.

Erwin Schröedinger (1932):

Erwin Schröedinger (1932):Shared Nobel Prize for Physics in 1933Used de Broglie’s and Einstein’s theories,

and the “Heisenberg uncertainty principle”.

Heisenberg uncertainty principle:It is impossible to simultaneously know exact

position and speed of a particle.You can only know one OR the other at any

given instant.

He said that electrons can have only quantized energies because of the requirement for only whole numbers of wavelengths to describe the electron wave.

Father of “wave mechanics”He proposed the “Quantum Mechanical

Model of the Atom”

G.P. Thomson (1937)Son of J.J. Thomson.Shares Nobel Prize with Clinton Davisson for

proving de Broglie’s theory.

*TODAY…We still do not know exactly what an electron is doing in an atom.*Wave equations from quantum mechanics can

be manipulated to produce a 3-D probability distribution of the electron, in an orbital specified by the quantum numbers.

Electron Probability Density:A mathematical or graphical representation

of the chance of finding an electron in a given space.

Dotted graphs correspond to the probability distribution.

Boundaries can be drawn based on the probability distribution.