ICSE Class 6 Chemistry, Unit 2: Elements, Compounds and Mixtures

What this unit aims at

All materials / objects found around us are either in solid, liquid or gaseous form and occupy space and have mass. In science, the term matter is used for all these materials. Chemically, matter can be classified as element, compound and mixture. In nature, matter occurs mostly in the form of mixture. Importantly, substances are required in their pure form that is done by the separation of the components of a mixture by different techniques. The use of any particular separation technique depends upon the properties of the components of the mixture.

Your child should be able to

• define elements as made up of identical atoms
• classify elements as metals and non-metals on the basis of their properties
• define compound and mixture and discuss the points of difference between the two
• use symbols of elements and molecular formulae of the compounds to represent their names as short hand notations
• separate different components of samples of some mixtures
• discuss the reasons for opting for a particular technique for separation of components of the mixture

Key concepts in this unit

• Element (a substance made up of identical atoms).
• Use of symbols as short hand notations of writing names of elements.
• Origin of symbols of elements.
• Names and symbols of first 20 elements.
• Molecules of elements contain atoms of the same element (O , N , 2 2
• H ). 2 Compound (two or more than two elements combine in fixed definite proportions to form a compound.
• Original properties of the constituent elements are
• lost and a substance with new properties is formed).: Molecules of compounds contain atoms of different elements. (H O, CO , NO , CaO, 2 2 2 ZnCl ). 2
• lost and a substance with new properties is formed).: Mixture (components of more than one substance combine in any proportion, original properties of the components are retained).
• lost and a substance with new properties is formed).: Difference between mixtures and compounds (on the basis of proportion of combination of components and their properties).
• lost and a substance with new properties is formed).: Separation techniques of mixtures into their components:
• lost and a substance with new properties is formed).: Sieving Sedimentation Decantation Filtration Evaporation Magnetic Separation Sublimation