The Chemistry of Carbon

Carbon atom is unique among other atoms, in that it is the atom that our life is built upon. All the compounds inside our body constitute of organic compounds, which have carbon and hydrogen atoms. Examples are amino acids, the building blocks of proteins, and DNA and RNA bases, which have carbon and hydrogen and nitrogen atoms in them. The cells of our body are all built from carbon compounds. Thus we see the importance of carbon in the body through these examples.

Carbon is a nonmetal, and has an atomic number of 6. Atomic numbers are the identity numbers for different atoms. Carbon can form a maximum of four bonds with other atoms. An example is the compound methane or CH4, in which the central carbon atom is attached to four hydrogen atoms to form a tetrahedral compound.

A bond can form from the overlap of two orbitals on two different atoms. Since in methane all bonds between the carbon and the four hydrogens are equivalent then there is a hybridization of the valence orbitals on carbon to form four equivalent orbitals called Sp3 hydrids. These in turn react or form bonds with the 1S orbital on hydrogen. There are two types of bonding between atoms depending on the relative electronegativity between them.

Equivalent bond means the sharing of the two bonding electrons equally between the two nuclei of the two atoms involved in the bond formation. Ionic compounds on the other hand are made from two different atoms as far as electronegativity is concerned. There is no sharing of electrons between the nuclei of the two atms, but one atom, the less electronegative waives its electrons to the more electronegative atom. An example is food salt or NaCl, in which the sodium ion which much less electronegative than chlorine gives its electron to the chlorine atom to form a negatively charged chloride ion.

Since carbon can make a maximum of four bonds, it can make double and triple bonds with other carbon atoms. Single bonds are called sigma bonds and are made by the overlap of two 1S orbitals on each carbon. Another way to make a sigma bond is by the overlap of two Pz orbitals on two different carbon atoms. The second and third bonds are called Pi bonds and they use two Px orbitals on two different carbon atoms or they can use two Py orbitals on two different carbon atoms.

The symmetry of sigma bond differs than the symmetry of the Pi bond and it is higher in the sigma bond. In addition sigma bonds are more stable than Pi bonds because the bonding electrons in sigma bonds are held closer to the positively charged nucleus. Carbon atom is the main atom in organic chemistry and it can form thousands of compounds with other carbon atoms or hydrogen and nitrogen or oxygen. Carbon cmpounds are widely used in the chemistry laoratory. Its compounds are used as solvents for organic and organometallic compounds.

Examples of organic solvents that have carbon are chloroform and methylene chloride, which are relatively inert organic compounds for reactions to take place.