Earth Science / Ms. Burt
Name_____________________
Hydrocarbons Any compound that contains mostly carbon and hydrogen is called a hydrocarbon. Hydrocarbons may be linear or branched, cyclic, or polymers. Most are named based on the longest chain of carbon‐carbon bonds. The names of hydrocarbons are a combination of a prefix that indicates the number of carbons and a suffix that indicates the type of covalent bond between the carbon atoms. # of carbon 1 2 3 4 5 6 7 8 9 10 Prefix Name Meth Eth Prop But Pent Hex Hept Oct Non Dec Suffix Names H
H
H
H
Single Covalent Bonds between the carbon atoms are ALKANES. They H
H
are named by adding “–ane” to the chemical prefix name for the length H
H
c
c
c
c
c
c
of the carbon chain. Branched or linear hydrocarbons have the general H
H
formula CnH(2n+2). These are considered Saturated hydrocarbons H
H
H
H
because they have the maximum number of Hydrogens. Hexane (C6H14) H
H
H H
At least one Double Covalent Bond between the carbon atoms are H
H
ALKENES. They are named by adding “–ene” to the chemical root name c
c
c
c
c
c
for the length of the carbon chain. Branched or linear hydrocarbons H
with one double bond have the general formula CnH(2n). A number and H
H H
H
H
hyphen are used to indicate the position of the double bond. These are considered Unsaturated hydrocarbons because they contain one or 2‐Hexene (C6H12) more carbon‐carbon double bonds. At least one Triple Covalent Bond between the carbon atoms are ALKYNES. They are named by adding “–yne” to the chemical root name CH3‐C≡C‐CH2‐CH2‐CH3 for the length of the carbon chain. Branched or linear hydrocarbons with one triple bond have the general formula CnH(2n‐2). A number and 2‐Hexyne (C6H10) hyphen are used to indicate the position of the triple bond. These are also considered Unsaturated hydrocarbons. Branched Hydrocarbons A branch is a short carbon chain that is bonded to the main chain and is named by adding –yl to the chemical prefix name for the number of carbons in the branch. For example a branch with 1 carbon is a methyl group; a 4 carbon branch is a butyl group. To name a branched hydrocarbon find the longest continuous chain of carbon‐carbon bonds – this is the part of the name that is either the alkane, alkene or alkyne. The carbon chain is then numbered to determine the position of the branch groups. The compound is then named as follows: #‐branch family. If there is more than one branch name as # ‐first branch‐#‐2nd branch family. If the groups are the same use the following prefixes to avoid repeating yourself: di‐2, tri‐3, tetra‐4 and separate the positions by commas. As examples: H
c
H
H
CH3 H
H
H
c
c
c
c
H
H
H
H
H
H
c
H
2‐methyl hexane H
c
H
H
CH3 H
H
H
c
c
c
c
H
CH2 H
H
H
H
H
CH3
2‐methyl‐3‐ethyl hexane c
H
H
H
H
H
H
c
c
c
c
H
CH3 H
H
H
H
H
c
H
3‐methyl hexane H
c
c
H
H
H
CH3 H
H
H
c
c
c
c
H
CH3 H
H
2,3‐dimethyl hexane c
H
H
Earth Science / Ms. Burt
Name_____________________
Practice with hydrocarbons 1. Draw the following hydrocarbons and state whether they are linear or branched Butane Octane Propene 2‐methyl butane 2,2,4,4‐tetramethyl pentane 3‐ethyl‐2‐methyl heptane 2. Name the following hydrocarbons and state whether they are linear or branched. 3.
a.
b.
c.
4.
Determine the molecular formula for the following: 3‐carbon alkane d. 4 carbon alkene 8‐carbon alkane e. 6 carbon alkene 43 carbon alkane f. 18 carbon alkene Determine the molecular formula from the following names a. Decane b. Decene c. 3‐propyl‐3‐methyl hexane d. 2,3,4‐trimethyl pentane