Quantum Mechanics

 Bohr's Theory & Model

  In order to fully understand Quantum Mechanics, we must also have a grasp on the Bohr Theory and Model as they serve as the foundation. 

 Some of the main points one most know for the Bohr Theory & Model are:
   
  1) Electrons exist in orbitals
       -> orbitals are found on energy levels/shells
       -> there are 2 electrons in the first orbital
       -> there are 8 electrons in the second orbital (called an octet when full)
       -> there are 8 electrons in the third orbital (called an octet when full)
       -> there are 18 electrons in the fourth orbital, etc.
   2) When electrons absorb energy, they move to a higher orbital
    3) As electrons fall from a higher orbital to a lower one, they release energy as a photon of light
   4) The Bohr Theory can be represented as either an Energy Level Model or the regular Bohr Model

EXAMPLE: The diagram shown above is an Energy Level Model of the atom Krypton (Kr). Instead of drawing individual dots, one can just write out the number of electrons that are to be found on each level and the number of protons and neutrons found in the nucleus.

EXAMPLE: The picture shown above are Bohr Models. Instead of colored dots, the neutrons & protons may be expressed with a number and their sign (p for protons & n for neutrons).



Quantum Theory
 The main points of the Quantum Theory are:
  
  1) An electron is like a cloud of negative energy or a wave
  2) Orbitals are areas in 3D space where electrons probably are
  3) The energy of an electron is in its vibrational modes (ie: the notes played on a guitar string)
  4) photons are produced when high energy modes change to lower energy modes 

 On each energy level, there are Orbitals:

S-Orbitals
-each orbital holds 2 electrons

 

P-Orbitals
-there are 3 sub orbitals that contain 2 electrons each (6 electrons in total)

D-Orbitals
-there are 5 sub orbitals that contain 2 electrons each (10 electrons in total)

 

F-Orbitals   
-there are 7 sub orbitals that contain 2 electrons each (14 electrons in total)

 
Diagram To Help Explain Orbitals:

  Consider the hotel above an atom. Each level in the hotel represents an energy level in the atom. Each floor on a level (distinguished by S,P,D,& F) represent the orbitals (distinguished by S,P,D, & F). On each floor there are rooms which represent the number of sub orbitals. The people standing in each room represent the number of electrons that exist in that orbital. Since the people have the ability to move around their levels, they don't have a fixed place but rather, a general area that they take up. In this sense, electrons are similar as they are thought of to be clouds of negative energy occupying a general area on their level.

*Credits:

->Bohr Diagrams:

http://lapse.nerdvana.org.au/comedy/pics/atom-bohr.gif

->S-Orbital:

http://img.sparknotes.com/figures/0/083ee1e849c82204c3d7c342d336a448/sorbital.gif

->P-Orbital:

http://img.sparknotes.com/figures/5/5578bdf1aec90e46e14325a580fdbf6a/porbital.gif

->D-Orbital:

http://img.sparknotes.com/figures/5/5578bdf1aec90e46e14325a580fdbf6a/dorbital.gif

->F-Orbital:

http://www.chemistry.ucsc.edu/~soliver/151A/Handouts/f-orbitals.gif

->Stick Figure:

http://3.bp.blogspot.com/_V5zRBX0DFfE/SaCpyJ6APBI/AAAAAAAAAGI/u0N19lXNlYs/s320/stick_figure.gif