Integrated SequencePhysics Chemistry Organic Biology

Web Resources

  click if a link is broken

Special points of emphasis

The Chemical Bond

Conjugated π Systems and Aromaticity

Molecular orbital theory is the key to understanding the Huckel's rule that an aromatic ring should have 4n + 2 π electrons. If you examine the molecular orbital diagram, you will see one, single lowest energy molecular orbital corresponding to π system hybridization, with successive energy levels corresponding to pairs of orbitals, if the total numbers of electron pairs is odd (number of electrons = 4n + 2), all bonding electrons will be paired; if not, then single electrons will go into the top level with spins parallel, which is not as stable.

The WikiPremed MCAT Course is a free comprehensive course in the undergraduate level general sciences. Undergraduate level physics, chemistry, organic chemistry and biology are presented by this course as a unified whole within a spiraling curriculum.

Please read our policies on privacy and shipping & returns.  Contact Us.
MCAT is a registered trademark of the Association of American Medical Colleges, which does not endorse the WikiPremed Course.

Creative Commons License
The work of WikiPremed is published under a Creative Commons Attribution Share Alike 3.0 License. There are elements of work here, such as a subset of the images in the archive from WikiPedia, that originated as GNU General Public License works, so take care to follow the unique stipulations of that license in printed reproductions. You can use the resources here for commercial or non-commercial purposes, but please give attribution and a link to the production credits and edit history of the resource. For the works here which began as my individual work, please attribute "John Wetzel, an author at".