ALKANES are straight-chain or branched-chain hydrocarbons in which all the bonds between carbon atoms are single covalent bonds. Alkanes are saturated hydrocarbons because the bond between the carbon atoms is a single bond. The simples alkane series hydrocarbon begins with CH₄ - methane. The next in series is ethane C₂H₆. Each member of the alkane series is formed by adding 1 carbon atom and 2 hydrogen atoms to the previous compound. Next in series is propane C₃H₈. Often is chemistry the names of the compounds in the same series will have the same ending, or suffix. Thus, the members of the alkane series all end with the suffix -ane, the same ending as the series name. The first part of the name, or the prefix, indicates the number of carbon atoms present in the compound. The prefix meth- indicates 1 carbon atom, the prefix eth- indicates 2 carbon atoms, the prefix pro- indicates 3, and so forth.

ALKENES are hydrocarbons in which at least one pair of carbon atoms are joined by a double covalent bond. Because they form double covalent bonds, alkenes are described as unsaturated hydrocarbons. The first member of the alkene series is ethene, C₂H₄. The next member is propene, notice how the ration continues 1 carbon : 2 hydrogens. Notice the diagram of ethene to the right, and the double covalent bond between the two carbon atoms.

Hydrocarbons in which at least one pair of carbon atoms is joined by a triple covalent bond are called ALKYNES. Like alkenes, alkynes are unsaturated because they share more than one covalent bond, in this case 3. The simplest alkyne is ethyne, C₂H₂, which is commonly known as acetylene. To the left you see the structural formula of ethyne. Notice the triple bond between the carbon atoms.

Some hydrocarbons are in the shape of rings. The best known of these type of hydrocarbons would be the aromatic hydrocarbons. The basic structure of an aromatic hydrocarbon is a ring of 6 carbon atoms joined by alternating single and double covalent bonds. The simplest aromatic carbon is benzene, C₆H₆. To the right you will see a diagram of benzene.

Alcohols are formed when a hydroxyl group is substituted in for a single carbon atom. To the left you see methanol CH₃OH. Notice hydroxyl replaces one hydrogen. Alcohols are used in some common substances such as beverages, de-icers, and medicines.

Organic acids are substituted hydrocarbons that contain the -COOH group, or carboxyl group. The picture to the left shows you the structural formula for methonoic acid, or what's commonly known as formic acid. Formic acid is found in certain stinging ants, this acid causes the ant bite to really hurt.

If an alcohol is combined with an organic acid, the resulting compound is called an ester. Many esters occur naturally like in fruits such as strawberries, bananas, and pineapples. Hydrocarbons can undergo substitution reactions in which one or more hydrogen atoms are replaced by an atom or atoms of fluorine, chlorine, bromine, or iodine. The family for these elements are known as the halogens, so the compounds formed are known as halogen derivatives. Freon is a refrigerant derived from methane CH₄, whose chemical formula is CCl₂F₂. Notice the 4 Hydrogen atoms have been replaced by 2 Chlorine atoms and 2 Fluorine atoms.

How can a thick, dark liquid like petroleum be transformed into gasoline, diesel fuel, plastic and other materials? To understand this you need to know that petroleum is actually a combination of a lot of different chemical compounds that have been mixed together. Each compound has its own particular boiling point, to seperate the compounds you need to heat the petroleum. Each compound will vaporize at its own boiling point; the lower the boiling point, the higher the vapor rises. This separation process is known as fractional distillation. The picture to the right shows a fractioning tower and the temperature at which the compounds vaporize. As the vapors cool, they condense and drain off through pipes on the sides of the tower and are collected. Petroleum products are significant not only as fuel, but also for the long chemical bonds they can form. Do you remember polar and non polar molecules. Depending on the compound, these molecules can link together to form long chains known as polymers. Think of a polymer as the type of chain used on a dog leash. One common petroleum polymer is plastic. Another common polymer is polypropylene, the compound used to make glues and carpets. Polymers can be made light and flexible or so strong that they can be used to make pipes, boats, and even automobile parts.

Biological polymers operate much like petroleum polymers. Long chains of molecules are linked together to make a larger and usually more complex structure. Many important biological polymers are found in your body; proteins, DNA, sugars, starches, fats, cholesterol, and carbohydrates to name a few. Proteins are large organic polymers called amino acids. Even though only 20 amino acids are found in nature, they can be arranged in so many ways that millions of different proteins exist. Proteins form tissues in your body like muscles, tendons, and even hair. In fact your body is 15% protein. Nucleic acids are another group of biological polymers that are essential for life. The most common nucleic acid is DNA - deoxyribonucleic acid. Of course you know that DNA controls all life processes.

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