Beginnings+of+Quantum+Mechanics

=Beginnings of Quantum Mechanics=

Bohr atom
Here are a couple of home-made drawings that go with the Bohr model. Note that these commom symbols are a very simplistic view of the atom and are only correct in that they contain electrons, protons, and neutrons. Several things are wrong with the drawings of the model which can trigger misconceptions: the shape of the electrons' orbits, the relative sizes of the particles, and the motion of the particles, just to name a few.
 * [[image:classic_orbital.jpg width="429" height="314"]] || [[image:planetary.jpg width="438" height="312"]] ||

The [|Bohr model of the atom], commonly referred to as "the planetary model", was widely accepted in the early 1900's.

Bohr depicted the hydrogen atom with a small, positively charged, centrally located nucleus encapsulated within negatively charged electrons with circular orbits. The electron was bound to the nucleus through electrostatic attraction.

Our first problem with this model arises from the emission spectrum of hydrogen. If the planetary model was true, a contunuous emission spectrum would be possible because the electrons could absorb and emit any amount of energy by making an appropriate adjustment in its orbital radius. However, since hydrogen only emits specific wavelengths of light it reasons that the atom can only hold special increments of energy, which contradicts the Bohr model. The model would either have to be adjusted or abandoned.

In efforts to adjust his model, Bohr suggested that the atoms could accept energies in discrete packets limited by the angular momentum of the orbitals. Integer multiples of where h is Planck's constant. But this proposal is only marginally correct.
 * The planetary model would not last long, it had several problems:
 * The [|electron's orbits]are not planetary
 * It could only explain the observed energy levels of hydrogen. No other atoms or molecules fit the model.
 * It could not explain chemical bonding
 * It could not explain why quantization occurrs


 * It was [|Erwin Schrodinger] who made the breakthrough connection between Bohr's stationary states and [|de Broglie's] electron wave properties which paved the way toward an understanding of [|quatum mechanics].

Wave/Particle Duality
The text "Chemical Bonding Clarified Through Quantum Mechanics" does a beautiful job of taking parallels between light and matter to create a thought continuum that brings about the meanings hidden within E=mc^2. The attached power point is a presentation of the explanation provided by George C. Pimentel and Richard D. Spratley.