Question

State four differences between – elements, compounds and mixtures with suitable examples.

Answer 1

1. Term:
   Elements – Pure substance made up of one kind of atoms only. e.g. Iron [Fe], Sulphur [S]
   Compounds – Pure substance made up of two or more elements, e.g. Iron sulphide [FeS]
   Mixture – Impure substance made up of two or more elements or compounds, e.g. Iron sulphur mixture.
   
2. Existence:
   Elements – Elements i.e. atoms of one kind are present on their own.
   e.g. Iron and sulphur exist on their own as elements iron and sulphur.
   Compounds – Components in a compound present in a definite proportion.
   e.g. Iron and sulphur are chemically combined in a fixed ratio in iron sulphide.
   Mixture – Components in a mixture present in any proportion.
   e.g. Iron and sulphur are mixed in any ratio in the mixture of iron and sulphur.
   
3. Properties:
   Elements – Elements have a definite set of properties. Elements classified into metal and non-metals each with its own properties.
   Compounds – Compounds have a definite set of properties.
   Elements of a compound do not retain their original properties.
   Mixture – Mixture does not have a definite set of properties. Components of a mixture do retain their original properties.
4. Separation:
   Elements – Elements occur on their own or as compounds and can be separated by chemical and physical methods.
   Compounds – Elements in a compound are chemically combined and can be separated by chemical methods only.
   Mixture – Components in a mixture are chemically mixed and can be separated by physical methods only.
5. Examples:
   Elements – Metals – Iron, copper, silver, gold.
   Non-metals – Sulphur, chlorine.
   Compounds – Iron sulphide, copper oxide, water.
   Sodium chloride, copper, sulphate.
   Mixture – Iron + sulphur, copper + silver, air, brass. Sodium chloride + water, copper sulphate + water.