Organic chemistry, also known as "Orgo or O-Chem" is the study of molecular structure and reactions pertaining to living matter. It is commonly referred to as the study of compounds that contain carbon.
Why spend an entire year learning about carbon?!?
Carbon containing compounds are the gateway to life. By studying organic chemistry one can have an appreciation for living organisms and the basis for life. One can also gain an understanding for organic chemistry contributions to health, medicine, pharmacology and industry.
Carbon
Organic Chemistry is the study of carbon. So let's review carbon.
Atomic number = 6
Electron configuration = 1s22s22p2
Valence Electrons
Definition: The electrons found in the outermost shell in the atom.
They are the electrons that can participate in bonding.
Note: Lone pair electrons are a subset of the valence electrons that do not participate in bonding.
1s22s22p2
The electrons in the second shell (2s22p2) represent carbon's valence electrons
2 +2 =4 So carbon has four valence electrons
In order to complete its octet it needs to share four more electrons
Octet Rule
Definition: the sum of all bonding electrons and non-bonding electrons on a given atom in the 2nd row of the periodic table will never be greater than 8
Exceptions to the Octet Rule:
Hydrogen and Lithium = 1 Valence Electron
Beryllium = 2 Valence Electrons
Elements in period 3 can occupy more than 8 valance electrons (e.g. Phosphorus and Sulfur)
So if carbon has four electrons it may accommodate four more electrons
How can it do so? It may gain two more bonds.
One bond = 2 electrons
Carbon "takes on" one of those electrons from a given bond towards its octet