ORGANIC+CHEMISTRY

= //__** ORGANIC CHEMISTRY - THE CHEMISTRY OF LIFE **__// =

To understand life as we know it, we must first understand a little bit of organic chemistry. Organic molecules contain both carbon and hydrogen. Though many organic chemicals also contain other elements, it is the carbon-hydrogen bond that defines them as organic. Organic chemicals make up your hair, your skin, your fingernails, and so on. The diversity of organic chemicals is due to the versatility of the carbon atom. Why is carbon such a special element? Let's look at its chemistry in a little more detail. Carbon (C) appears in the second row of the periodic table and has four bonding electrons in its valence shell (see our Periodic Table module for more information). Similar to other non-metals, carbon needs eight electrons to satisfy its valence shell. Carbon therefore forms four bonds with other atoms (each bond consisting of one of carbon's electrons and one of the bonding atom's electrons). Every valence electron participates in bonding, thus a carbon atom's bonds will be distributed evenly over the atom's surface. These bonds form a tetrahedron (a pyramid with a spike at the top), as illustrated below:

Organic chemicals get their diversity from the many different ways carbon can bond to other atoms. The simplest organic chemicals, called hydrocarbons, contain only carbon and hydrogen atoms; the simplest hydrocarbon (called methane) contains a single carbon atom bonded to four hydrogen atoms: **METHANE CAN ALSO BE DRAWN AS A STICK DIAGRAM THUS:**

__MULTIPLE BONDING__ Bonding between non-metal atoms is covalent bonding. It can also be single, double or triple bonding, according to the number of electrons that are shared between two atoms. CARBON is able to form single, double and triple bonds with another CARBON ATOM. If two C atoms form a single bond, sharing one electron, then each must form bonds other bonds to fill the valence shell. SINGLE CARBON BOND = ETH**ANE** (C2H6)

DOUBLE CARBON BOND = ETH**ENE (C2H4)**

TRIPLE CARBON BOND = ETH**YNE** (C2H2)

=__** HYDROCARBON GROUPS **__= HYDROCARBONS FALL INTO THREE GROUPS ACCORDING TO THE NUMBER OF CARBON BONDS: Alkanes occur in a series CH 4 / C 2 H 6 / C 3 H 4 / C 4 H 10 The smallest of the Alkenes is Ethene (C 2 H 4 ). The next is Propene (C 3 H 6 ). Alkenes go on to form long chains or __Polymers__. These in different sizes form __PLASTICS.__ Alkenes are named the same way as Alkanes except they end in '**-ene**'
 * ** __ALKANES__ ** - __single bonds between Carbon atoms.__ Their formula can be determined using the formula C n H 2n +2, where n = the number of Carbon atoms.
 * __**ALKENES** - double bonds between Carbon atoms__. Their formula can generally be determined by C n H 2n The number of atoms of Hydrogen is exactly double the number of atoms of Carbon.
 * ** __ALKYNES__ ** - __triple bonds between Carbon atoms__. The way to determine their formula is C n H 2n-2 Their name ends in '**-yne**'

**NAMING SIMPLE HYDROCARBONS** Alkanes are named in the following way. The prefix depends on the number of Carbon atoms. The ending depends on the number of bonds that form between these


 * ===METH........................=== || ===1........................=== ||
 * ===ETH=== || ===2=== ||
 * ===PROP=== || ===3=== ||
 * ===BUT=== || ===4=== ||
 * ===PENT=== || ===5=== ||
 * ===HEX=== || ===6=== ||
 * ===HEPT=== || ===7=== ||
 * ===OCT=== || ===8=== ||
 * ===NON=== || ===9=== ||
 * ===DEC=== || ===10=== ||

EXAMPLE: THIS ATOM HAS SIX CARBON ATOMS WITH A DOUBLE BOND - C6H12