Everything Science Grade 12

CHAPTER 1. ORGANICMOLECULES 1.7

C C

H

H

H

H

Figure 1.7: An unsaturated hydrocarbon

We will now go on to look at each of the acyclic, aliphatic hydrocarbongroups in more
detail. These groups arethe alkanes, the alkenesand the alkynes.

The Alkanes ESCK

The alkanes are hydrocarbons that only contain single covalent bonds between their
carbon atoms. This means that they are saturated compounds and are quite unreactive.
The simplest alkane hasonly one carbon atom and is called methane. This molecule
is shown in figure 1.8.

CH H

H

H

(a) (b) CH 4

Figure 1.8: The structural (a) and molecular formula (b) for methane

The second alkane in the series has two carbonatoms and is called ethane. This is
shown in figure 1.9.

CH

H

H

C H

H

H

(a) (b) C 2 H 6

Figure 1.9: The structural (a) and molecular formula (b) for ethane

The third alkane in theseries has three carbonatoms and is called propane (Figure
1.10).