Category : 4th Class
Matter and Materials
Anything that occupies space and has mass is called matter. Everything around us is made up of matter. Matter is made up of atoms. Water bottle, school bag, rubber, pencil are all made up of matter.
States of Matter
Matter exists in three forms - solid, liquid and gas. Matter can change from one form in other on heating and cooling.
Changes Around Us
Matter is constantly changing around us. Changes are of two types — physical changes and chemical changes. In physical change, no new substance is formed. Breaking of glass, melting of ice into water are some examples of physical change. When ice melts the solid water turned to liquid water. It doesn't turn into food or cold drink or anything new. It remains water. Physical changes can be reversed.in a chemical change, new substance is formed. Changing of milk into curd is an example chemical change. Similarly burning of paper, making of vegetable dishes from raw vegetables, bursting of crackers are some other examples of chemical changes. Unlike physical changes, chemical changes cannot be reversed.
Minerals are chemical substances that occurs in nature. They are formed due to natural processes within the earth. They may be simple substances or very complex Rocks are formed of minerals. Examples of non-metallic minerals are limestone, magnesite, mica, etc. There are metallic minerals also such as gold, silver, iron, etc. Our body needs some minerals such as calcium, sodium and iron in very small quantities for healthy growth. The bulk of minerals is used for industrial needs as manufacturing of building materials, vehicles, for fuels and for making jewellery.
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