Organic Chemistry and Heat Unit  
Using methane, CH4, as a starting point we can add more carbons, one at a time, and more hydrogens to fill out the bonds on the carbons. This first group is called the alkane series and it has the general formula:  
CnH2n+2
Alkane series
Name Formula mol. wt. m.p. b.p.
methane CH4 16.04 -182.48o -164oC
ethane C2H6 30.07 -183.3  -88.63
propane C3H8  44.11  -189.69  -42.69
butane C4H10 58.13 -138.35 -0.5
pentane C5H12 72.15 -129.72 36.07
hexane C6H14 86.18 -95 68.95
heptane C7H16 100.21 -90.61 98.42
octane C8H18 114.23 -56.79 125.66
nonane C9H20 128.66 -51 150.80
decane C10H22 142.99 -29.7 174.1
undecane C11H24 156.32 -25.59 195.90
Look at the list very carefully.  Each successive compound increases by only CH2. Also the molecular weight increases by only 14.03, that is CH2.   It also seems that as the length of the carbon chain increases from 1 to 11 the melting point increases as well as the boiling point.
 
All of the above are straight-chain alkanes. That is, each additional carbon is added to the end to form one long continuous chain and there are only single bonds in the main chain of the molecule.

For example:


              propane                                                                    octane
 
Propane has three carbons in a main chain, hence, prop, and there are only single bonds in this main chain therefore (ane). Octane has eight C's in a main chain hence, oct, and again the main chain has only single bonds between beach carbon therefore it is an "ane". Both of the above are members of the alkane series. Draw several more to verify for yourself how these compounds are put together.
 
IUPAC Rules For Naming Organic Compounds.
(International Union of Pure and Applied Chemists)
1. Find the longest continuous carbon chain. Count the number of carbons in it and determine the prefix.
 
2. Check to make sure that all the bonds in this long chain are single. The ending will be "ane"
 
3. Put the prefix and ending together.
 
Naming compounds with side chains
How do we name something like this? 
 
First find the longest carbon chain. It has 11 carbons in it therefore this compound is a "undec" something. Check to see if it contains only single bonds. It does, therefore it is an "ane" as well. The compound is a "undecane". What about the C-C group?
 
Two carbons is "eth" and it has single bonds therefore it is ethane but it is attached to the longer chain. Take the "ane" off and add "yl". This is an ethyl group. If you count bonds it is not C2H6 but it is in fact C2H5-. The "-" indicates the point of attachment to the long undecane chain. So this compound is ethylundecane. But where is the "ethyl" group attached. Start counting from the end of the undecane. The ethyl group is either 5 from one end or 6 from the other end. When this happens always choose the lowest number. So we can name this as  5-ethylundecane. That is, an 11 carbon alkane called undecane with an ethyl group stuck on it at the 5th carbon from the end.
 
IUPAC Rules For Naming Branched Compounds
1. Determine the longest continuous chain, this will be the parent chain. Give the parent chain a prefix matching the number of carbon's in it.
 
2. Assign #'s to each C of the parent chain so that the numbers of all attached side pieces add up to the smallest sum.
 
3. Determine the correct name for each branch or other atom or group.
 
4. Attach the name of the alkyl group or other substituent to the name of the parent as a prefix. Place the location # in front and separate from the name by a hyphen.
 
eg.     3-methyl-heptane
 
Parent chain is 7 carbons long with all single bonds, therefore heptane. Side group is one carbon, therefore "meth" and because it is attached to the parent we add "yl" so we get methyl. The methyl group is attached to the parent chain at carbon number 3 not carbon number 5. Count for yourself. Put it all together 3-methylheptane.
 
5. When 2 or more groups are attached, name each, and locate them by number. Always use hyphens to separate the #'s from each other.
 
eg.  3-ethyl-5-methyl-octane
 
Ethyl comes before methyl alphabetically, it just happens to come that way numerically in this example as well.
 
eg.  4-ethyl-3-methyl-octane
 
In this example ethyl still comes first alphabetically before methyl. The numbers that locate their point of attachment go with them.
 
6. When 2 or more of the substituents are identical, use special prefixes such as "di" for 2, "tri" for three and "tetra" for 4 and specify the location #'s of every group.   eg. 
2,4-dimethyl-hexane (OK)    2-methyl-4-methyl-hexane (NO)     3,5-dimethyl-hexane(NO)
 
7. When identical groups are on the same carbon in the parent chain, repeat the number on the parent 
carbon.    eg. 
 3,3-dimethyl-pentane (OK)    3-dimethyl-pentane (NO)     3,3-methyl-pentane (NO)
 
Add-on Substitution Groups
The following are substitution groups that can be added on to a main parent chain.

methyl

ethyl

n-propyl


iso-propyl


n-butyl


sec-butyl


tert-butyl


In addition to the above there are the halogen substitution groups:
F is fluoro
Cl is chloro
Br is bromo
and I is iodo

Go to Organic Worksheet #1 - Simple Chain Nomenclature