This is the first of our GCSE Chemistry quizzes on organic chemistry. Over ninety percent of all chemical compounds are classified as organic compounds. They were given this name because scientists once thought that they could only be made naturally - not unnaturally by scientists in a laboratory. However, in 1828, Friedrich Wohler made the naturally occurring organic compound urea in his laboratory which opened the door to making others from simpler materials.
But what exactly is organic chemistry? Essentially, it is the chemistry of carbon compounds but keep in mind that not all carbon compounds are organic chemicals, for example, carbon dioxide. Essentially, an organic compound contains at least one carbon atom in the compound that is joined to at least one hydrogen atom. If a molecule contains chains of two or more carbon atoms, bonded to each other and to other elements, that is also recognised as being an organic chemical. Organic compounds are always covalent, but some can show some slight charateristics of ionic compounds e.g. soluble in water.
Organic chemicals can be grouped into families which contain compounds with similar properties. This happens because they are based on chains of carbon atoms. Take for example the alkane family. Methane is the simplest alkane and has one carbon atom. Ethene has two carbon atoms and its properties are very similar to methane. Octane has eight carbon atoms and although it is a liquid and not a gas like methane and ethane, it still has similar chemical properties to those two substances. There is a general formula that can be used to predict the exact formula of any member of a family of organic chemicals.
For your GCSE exam, you will learn about the alkane and alkene family as you study crude oil. You will also learn about polymers that are made from organic chemicals. In addition to these, you are expected to know about three other organic chemical families - the alcohols, carboxylic acids and esters. You will need to be able to recognise and represent the structures of alcohols and carboxylic acids in the form of structural formulae and also as the more familiar chemical formulae. You may be given data and other information in your exam and asked to evaluate and compare the social and economic advantages and disadvantages of these chemicals. You won't be asked to remember the names of more than a few of these chemicals, different exam boards have slightly different requirements but your teacher will make it clear which you need to know.
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