From Academic Kids
Organic chemistry is the scientific study of the structure, properties, composition, reactions, and synthesis of organic compounds. Organic compounds are composed of carbon and hydrogen, and can possibly contain any of the other elements such as nitrogen, oxygen, phosphorus, and sulfur.
Organic chemistry as a science is generally agreed to have started in 1828 with Friedrich Woehler's synthesis of the organic, biologically significant compound urea by accidentally evaporating an aqueous solution of ammonium cyanate NH4OCN.
Characteristics of organic substances
The reason that there are so many carbon compounds is that carbon has the ability to form many carbon chains of different lengths, and rings of different sizes (catenation). Many carbon compounds are extremely sensitive to heat, and generally decompose below 300?C. They tend to be less soluble in water compared to many inorganic salts. In contrast to such salts, they tend to be much more soluble in organic solvents such as ether or alcohol. Organic compounds are covalently bonded.
Aliphatic compounds are organic molecules that do not contain aromatic systems. Typically, they contain hydrocarbon chains.
Aromatic compounds are organic molecules that contain one or more aromatic ring system.
Heterocyclic compounds are cyclic organic molecules whose ring(s) contain at least one heteroatom. These heteroatoms can include oxygen, nitrogen, phosphorus, and sulfur.
Polymers are a special kind of molecule. Generally considered "large" molecules, polymers get their reputation regarding size because they are molecules that consist of multiple smaller segments. The segments could be chemically identical, which would make such a molecule a homopolymer. Or the segments could vary in chemical structure, which would make that molecule a heteropolymer. Polymers are a subset of "macromolecules" which is just a classification for all molecules that are considered large.
Polymers can be organic or inorganic. Commonly-encountered polymers are usually organic (e.g., polyethylene, polypropylene, Plexiglass, etc.). But inorganic polymers (e.g., silicone) are also familiar to everyday items.
Determining the molecular structure of an organic compound
Currently, there exist several methods for characterizing an organic compound. In general usage are (in alphabetical order):
- Crystallography: This is the most precise method; however, it is very difficult to grow crystals of sufficient size and high quality to get a clear picture, so it remains a secondary form of analysis.
- Elemental Analysis: A destructive method used to determine the elemental composition of a molecule.
- Infrared spectroscopy: Chiefly used to determine the presence (or absence) of certain functional groups.
- Mass spectrometry: Used to determine the molecular weight of a compound and the fragmentation pattern.
- Nuclear magnetic resonance (NMR) spectrometry
- UV/VIS spectroscopy: Used to determine degree of conjugation in the system
See Analytical chemistry for additional methods.
Most of the time spent in an introductory organic chemistry class involves learning the processes used to manufacture organic molecules. For details, see Organic reaction