Carbon ring

Carbon rings are rings of carbon atoms. Many organic compounds that are essential to life on earth are formed by carbon rings. The structures of organic compounds commonly are represented by simplified structural formulas, which show how atoms are linked by covalent bonds by using short lines. Rings of five and six carbons are by far the most common, as they allow bond angles close to the ideal angle of 109.5°. Rings of five are called cyclopentanes. Cyclohexanes consist of six carbons bonded together by single bonds, and benzenes consist of six carbons bonded together by alternating single and double bonds. When drawn out, carbon rings are usually represented as polygons in which each point represents a carbon, and the hydrogen or other molecules or atoms complete the bonding requirements of the respective carbon atoms. Rings of three and four are possible, but with bond angles of 60° and 90°, they have a larger ring strain and are unstable. The simplest carbon ring structure is actually called cyclopentane, with five carbons. Ring strain decreases with an increasing number of carbon atoms until cyclohexane, which is a six-membered ring. After cyclohexane, ring strain increases again until cyclotetradecane, with 14 carbon atoms. Ring strain starts to decrease again, but slowly; very large rings have little ring strain, as they are almost linear.
Compounds such as cycloalkenes or benzene, or the non-benzenoid aromatic tropone, have a single carbon ring; rings can also be joined, with some atoms being a part of more than one ring.
Cyclopentane:
When drawn out, cyclopentanes are often in the shape of a pentagon. They have two atoms attached to each carbon in order to fulfill the octet rule. However, the ring is not flat like it is shown in drawings. In reality, carbon atom that is farthest to the left is tipped up from the ring. Though the shape of the ring is in a pentagon, the carbons still attempt to resemble the shape of a tetrahedral.
Cyclohexane:
Cyclohexane, which consists of a 6-carbon ring with all single bonds, is also not flat. The ring formation attempts to attain the bond angles for the tetrahedral carbon atoms. Free rotation around carbon-carbon single bonds, allows molecules to exist in a many different molecular arrangements called conformations. Confirmations tend to change quickly, even at room temperature. This causes the atoms and/or molecules that are attached to each carbon to move around the carbon ring at a rapid rate, changing the shape of the carbon ring. Cyclohexane rings are extremely common and important in biological compounds.
There are two common forms of cyclohexane, called the chair form and the boat form. The chair form of cyclohexane, which tips up from the left side and down from the right side, is the most stable conformation of cyclohexane since all of the hydrogen atoms are as far apart from each other as possible. Another type of cyclohexane ring is called the boat form in which the carbon atoms to the left and the right are tipped up.
Benzene:
The benzene ring consists of six carbon atoms covalently bonded together in a planar, hexagonal ring. There are three double bonds that are found in benzene rings, which means that only one hydrogen is bonded to each carbon. Each carbon is bonded to the ones adjacent to it in both a single and a double bond. Benzene rings can be portrayed in two different manners. One of these alternating double bonds, called a resonance structure. The other consists of the traditional hexagonal structure with a circle inside of it.

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