Chemistry Unit 1 - GCSE

HYDROCARBONS

Hydrocarbons are mainly used as fuel. They consist only of hydrogen and carbon, each carbon has 4 covalent bonds attached. Each hydrogen has only 1 covalent bond attached.

Crude oil contains both alkanes and alkenes (although mostly alkenes). they have different properties and its all down to their structure. 

Alkenes:

 - have chains of carbon atoms with one or more double covalent bonds. (double covalent bond - atoms sharing two pairs of electrons, a double bond counts as 2 of a carbon atoms 4 attached bonds)

 - unsaturated hydrocarbons - double bonds can open up and let things join on.

-  decolourise bromine water - form bonds with bromine (bromine goes clear)

 - formula for all alkenes containing one double bond = CnH2n

 - more reactive - due to double bond which will open up and attach to other                                       things. 

                          - form polymers by a double bond opening up and 'holding hands'                             in a long chain.

 - burn with smoky flame producing soot (carbon)

Ethene C2H4      …