Unsaturated compounds are compounds in which carbon atoms are joined together by double or triple bonds.
Alkenes Organic compounds with a double bond between the carbon atoms are members of the Alkene family of Organic compounds.
The Alkenes are more reactive than the Alkanes (Alkanes are saturated compounds. They have a single bond between carbon atoms) as the double bond is capable of 'opening up' and bonding with other elements
or compounds through an addition reaction.
The test for the double bond is Bromination, i.e. the addition of Bromine water. When testing the gas ethane for the double bond, bromine water is added to a test tube of the gas. The red bromine water turns colourless. This is a positive result indicating a double bond.
The reaction proceeds as follows:
The bromine water is added...
...the double bond swings open to accept the bromine atoms...
It's called prop-1-ene because the double bond is on the 1st carbon atom.
Alkynes
Alkynes are organic compounds which contain a triple bond between the carbon atoms. They are very reactive and volatile and like the Alkenes undergo addition reactions and decolourise bromine water.
A common example, Ethyne (Industrially know as Acetylene), burns in oxygen at a very high temperature and is used for cutting and welding steel.
