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CARBON AND ITS COMPOUND

Organic - pertaining to life Living or was once living Organic Chemistry - The chemistry of carbon compounds Carbon is well suited for life because it is the most versatile element in terms of bonding.

.Carbon (C) appears in the 2nd row of the periodic table and has atomic number of 6. Given our discussion of electron shells it is easy to see that carbon has 4 electrons in its valence shell. Since carbon needs 8 electrons to fill its valence shell, it forms 4 bonds with other atoms (each bond consisting of one of carbon's electrons and one of the bonding atom's). 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, as illustrated below:

Carbon can form four bonds. They can be single, double or triple bonds. Carbon will not form diatomic molecules like other small atoms do.It can form long carbon chains containing strong, short, covalent bonds.

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Allotropes forms of the same element that differ in their bonding There are several allotropes of carbon

Diamond tetrahedral network of carbon atoms (every atom is locked into place (hardness)

Graphite sheets can slide over each other (lubricant)

Amorphous carbon charcoal, soot, coke Amorphous has not set arrangement of atoms. It has irregular patterns of high surface area, deep caves that can trap other molecules

Fullerenes spherical molecules (60 atoms) see page 807, mostly experimental at this point.

Hydrocarbons

.molecules that contain only hydrogen and carbon

Fossil Fuels

Natural gas - mostly methane

Crude oil - mixture of hydrocarbon chains from propane to butane, octane and longer Components separated using fractional distillation (see page 823)

Coal - mostly impure carbon (coke - pure carbon from coal, charcoal - pure carbon from wood)

Types of Formulas (examples) Compound hexane

.Empirical formula. Molecular formula .Structural formula .Condensed structural formula

CLASSIFICATION OF ORGANIC COMPOUNDS

ALKANES - Compounds that contain only hydrogen and single bonded carbons. (carbon chains surrounded by hydrogens). Named with an ane ending that is preceded with a prefix which gives how many carbons that are in the carbon chain.

An organic molecule (hydrocarbon) is formed when carbon bonds to hydrogen. The simplest hydrocarbon consists of 4 hydrogen atoms bonded to a carbon atom (called methane): Methane

In addition to binding to hydrogen, carbon can also bind to other carbon atoms, as illustrated below:

In fact the uniqueness of carbon comes from the fact that it can bind to itself. Carbon atoms can form long chains:

branched chains: Ethane Hexane

Carbons can form in ring shapes Cyclohexane

Saturated vs Unsaturated Hydrocarbons

Saturated carbons are single bonded and have a greater compliment of hydrogen. ( hence, saturated )

Unsaturated carbons are generally doubled bonded and thus are attached to fewer hydrogen.

In fact, there appears to be almost no limit to the number of different structures that carbon can form. To add to the complexity of organic chemistry, neighboring carbon atoms can form double and triple bonds in addition to single carbon-carbon bonds:

Single, double, and triple bonds :

Keep in mind that each carbon atom forms 4 bonds. As you increase the number of bonds between carbon atoms, the number of hydrogen atoms in the molecule decreases.

.Nomenclature (naming compounds): The simplest hydrocarbons are those that contain only carbon and hydrogen. As we have seen, these come in three varieties: 1) alkanes, molecules with only single bonds, 2) alkenes, those with one or more double bond and 3) alkynes, those with one or more triple bond.

Basic organic chemistry can be thought of as a molecular Erector Set, if you know the number of carbon atoms and the type of bonds in a molecule, you can build the molecular structure

To describe the number of carbon atoms in a hydrocarbon, chemists use prefixes in the molecule's name. The first 10 prefixes used in organic chemistry are shown below. To complete the hydrocarbon name, the prefix is attached to the ending of the root word (drop the alk- from the words alkane, alkene or alkyne) to describe the type of bonding on the molecule. Hydrocarbon prefix

# of C atoms name formula structure Meth 1 methane CH4 Eth 2 ethane C2H6 Prop 3 propane C3H6

Hydrocarbon prefix # of C atoms name formula structure

but 4 butane C4H10

pent 5 pentane C5H12

hex 6 hexane C6H14

hept 7 heptane C7H16

oct 8 octane C8H18

non 9 nonane C9H20

dec 10 decane C10H22

14.Alkanes (Single Bonds)

As we have discussed, each carbon atom has 4 bonds. As you add carbon to a molecule, the empty carbon bonds are filled with hydrogen atoms (or other elements, as we will soon see). You can calculate the number of H atoms in the simple alkanes. The number of H atoms in a simple alkane equals two times the number of carbon atoms plus 2, or (2n + 2), where n is the number of carbon atoms in the molecule.

Alkenes (double bonds)

The simple alkenes have 1 double bond and 2 fewer H atoms in the molecule; the number of H atoms in the simple alkenes = (2n). Simple alkynes contain 1 triple bond 2 fewer H atoms than the alkene, or (2n - 2) H atoms.

Functional Groups In addition to carbon and hydrogen, hydrocarbons can also contain other elements. The alcohols, for example, are a group of hydrocarbons in which a hydroxol (-OH) group is bound to a carbon skeleton.

These compounds are named like the simple hydrocarbons, a prefix attached to a root ending (-anol for the alcohols). Thus ethanol, is a 2 carbon alcohol with the structure:

Most people are familiar with this organic compound as it is the active ingredient in "alcoholic" beverages such as beer and wine.

.While the simple hydrocarbons are important, they do not themselves commonly occur in living organisms (except for during the occasional bout of methane flatulence).

.The simple hydrocarbons are the building blocks of more complex molecules that make up living organisms. In the next few weeks, I will introduce some of these molecules and their biochemistry, the chemistry of life. Alcohol (Hydroxyl Group) Aldehyde (Carbonyl Group) Ketone (Carbonyl Group) Carboxylic Acid (Carboxyl Group) Amine (Amino Group) Amino Acid (Amino Group + Carboxyl Group)

Great site that helps to match the funtional group to its structure.http://biology.clc.uc.edu/courses/bio104/carbon.htm Many important organic chemistry molecules contain oxygen or nitrogen. It's a good idea to memorize the names and structures of these functional groups.

.ALKANES SUBSTITUDED WITH HALOGENS Give the position of the halogen (F, Cl, Br, or I) and then give the name of the halogen with an "o" ending. 3-chloro-2-methylpentane bromochloroiodomethane

.Conformational isomers - molecules with the same structure but with different bond rotation. Molecules with single bonds can rotate about the single bond. These are the same compound. They have the same melting point, the same boiling points and the same chemistry. The higher the temperature the faster they change back and forth from one form to the other. Example: cyclohexane (chair and boat conformation)

Structural isomers - molecules that have the same molecular formula but have different structural formulas. These are different compounds with different melting points and different chemistry Examples C5H12 (pentane, 1 methyl butane, 2,2 dimethyl propane)

SUBSTITUTED ALKANES Fisher Projection - a way to show the 3-dementional character of a molecule. Examples: CHFClI A carbon that has 4 different groups bonded to it is called a chiral carbon. Enantiomers - (mirror image isomers) - two arrangements around a chiral carbon that cannot be rotated in such a way as to be superimposed on each other.

They are different molecules that have the same formula, same boiling points and much of the same chemistry. Their chemistry differs when they are reacting with molecules that also have chiral carbons. (biological systems) They also rotate polarized light in opposite directions. Vitamin C is an example of this type of molecule

.UNSATURATED HYDROCARBONS If the molecule is filled to capacity with hydrogen the compound is saturated (alkanes). If the molecule is cyclic, contains a double bond or contains a triple bond it is unsaturated. Saturated fats are from animals and are not good for you. Unsaturated fats are from plants

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