Just what is organic? The term "organic" often conjures up the image of life; something very separate from inanimate or not possessing any traits commonly attributed to being alive. That is, when something is alive and it therefore is organic. In the supermarket, we are used to seeing the "organic" label to designate something special, something more connected to nature. However, the term organic in chemistry has a very specific definition involving chemicals and chemistry that involves carbon. As discussed below, there a strong diversity of chemistry associated with organic compounds.
Hybridization was introduced to explain molecular structure when the valence bond theory failed to correctly predict them. It is experimentally observed that bond angles in organic compounds are close to 109o, 120o, or 180o. According to Valence Shell Electron Pair Repulsion (VSEPR) theory, electron pairs repel each other and the bonds and lone pairs around a central atom are generally separated by the largest possible angles.
There are many types of chemical bonds and forces that bind molecules together. The two most basic types of bonds are characterized as either ionic or covalent. In ionic bonding, atoms transfer electrons to each other. Ionic bonds require at least one electron donor and one electron acceptor. In contrast, atoms with the same electronegativity share electrons in covalent bonds, because neither atom preferentially attracts or repels the shared electrons.
The increasingly large number of organic compounds identified with each passing day, together with the fact that many of these compounds are isomers of other compounds, requires that a systematic nomenclature system be developed. Just as each distinct compound has a unique molecular structure which can be designated by a structural formula, each compound must be given a characteristic and unique name. As organic chemistry grew and developed, many compounds were also given trivial names.
It is incorrect to present the value of 15.7 for the pKa of water, yet this value has entered the fields of organic chemistry and biochemistry. The proposed value of 1.8 x 10-16 for the Ka of water cannot be justified with thermodynamic data, nor are there any experimental data to support this value. In fact, 1.8 x 10-16 is a hypothetical value that was arrived at using specious arguments to justify an incorrect assumption that the relative strengths of acids were unaffected by changing solvent.
