Organic chemistry is the branch of chemistry in which carbon compounds and their reactions are studied. A wide variety of classes of substances such as drugs, vitamins, plastics, natural and synthetic fibers, as well as carbohydrates, proteins, and fats consist of organic molecules. Organic chemists determine the structures of organic molecules, study their various reactions, and develop procedures for the synthesis of organic compounds. Organic chemistry has had a profound effect on life in the 20th century: It has improved natural materials and it has synthesized natural and artificial ma terials that have, in turn, improved health, increased comfort, and added to the convenience of nearly every product manufactured today.
The advent of organic chemistry is often associated with the discovery in 1828 by the German chemist Friedrich Wöhler that the inorganic, or mineral, substance called ammonium cyanate could be converted in the laboratory to urea, an organic substance found in the urine of many animals. Before th is discovery, chemists thought that intervention by a so-called life force was necessary for the synthesis of organic substances. Wöhler's experiment broke down the barrier between inorganic and organic substances. Modern chemists consider organic compounds to be those containing carbon and one or more other elements, most often hydrogen, oxygen, nitrogen, sulfur, or the halogens, but sometimes others as well.
Carbon is unique amoungst the elements in that it can form an enormous number of compounds, and a variety of different structures. It can form single, double and triple bonds; rings, branched chains, branched and interlocked rings. An example of the unique behavior of carbon in forming compounds is the fact that thousands of hydrocarbons exist (compounds of carbon and hydrogen only) wereas only two compounds of, for example, hydrogen and oxygen exist (water and hydrogen peroxide).
The properties of carbon.....
| Atomic Number | : 6 |
| Shells | : 2, 4 |
| Melt | : 3500o C |
| Covalent Radius | : 0.91 Å |
| First Ionization Potential | : 11.260 V |
| 2nd Ionization Potential | : 24.383 V |
| Density @ 293 K | : 2.62 g/cm3 |
| Heat Of Vaporation | : 355.80 kJ/mol |
| Elektrical conductivity | : 0.00061 106/cmΩ |
| Atomic Weight | : 12.011 |
| Filling Orbital | : 2p2 |
| Boil | : 4827 O C |
| Atomic Volume | : 4.58 cm3/mol |
| Electronegative | : 2.55 cm3/mol |
| Oxidation states | : ± 4.2 |
| 3rd Ionization Potential | : 47.887 V |
| Specific Heat | 0.71 J/gK |
| Thermal Conductivity | : 1.29 W/cmK |
Carbon is able to form 4 single bonds, all homogenous. This is due to carbon forming hybrid orbitals:
Electronic Structure of Carbon = 1S2 2S2 2P2 . The 2S and 2P orbitals combine and form hybrid orbitals known as SP3 orbitals (1S + 3P orbitals) this makes 4 equivalent orbitals which are able to bond singley. In the case of double bonds 1 S orbital and 2 P orbitals combine to form a hybrid known as an SP2 hybrid. Triple bonds form by way of SP hybridization.
The study of compounds of carbon forms the discipline known as organic chemistry. This is not strictly correct though, as there are compounds of carbon in inorganic chemicals. Organic chemistry was first given its name derived from the Greek Organon - part of the body ; this is because it was first believed that organic compounds could only be produced from living organisms. Today there are over 6 million organic chemicals known, a figure which is rises day by day.
Organic compounds are divided into classes according to their molecular structure, and their properties are interpreted in terms of the chemistry of their functional groups.
Organic compounds each fall into catagories known as a homologous series:
The homologous series has 4 major criteria by which aorganic compounds are catagorized: 1. Have the same general formula e.g Alkanes have CnH2
n+2
2. Thet have a molecular mass 14 (CH2) greater than the preceding member i.e C4H10 and C5H12
3. They have similar chemical properties.
4. Thet have physical properties showing steady graduation e.g B.P will increase with RMM.
Organic compounds are named systematically by using nomenclature. All organic compounds can be named by the guidlines set by IUPAC. This includes the naming of the functional group and also the carbon chain:
1 carbon = meth
2 carbons = eth
3 carbons = prop
4 carbons = but
5 carbons = pent
6 carbons = hex
7 carbons = hept
etc........
Organic chemistry concerns itself with both the physical and chemical properties of organic compounds. Physical properties include size and shapes of molecules and how the behave under certain conditions ; chemical properties deals with how the compounds react, both with other organic compounds and also inorganic reagants. There are three main ways by which organic compounds react:
Classes of Organic Reaction...........
1. Addition A-B + X-Y -------> X-A-B-Y
2 Elimination X-A-B-Y ---------> A-B + X-Y
3 Substitution A-X + Y ---------> A-Y + X
All classes of organic reaction fall into one of these catagories.
