Impure Substances: Mixtures
A mixture is one which contains two or more different kinds of particles (atoms or molecules). In other words, a mixture contains two or more pure substances ixed together. For example, salt solution is a mixture of two pure substances : salt and water. And milk is a mixture of water, fat and proteins, etc.All the mixtures are impure substances because they contain more than one kind of particles. Some of the examples of the mixtures are : salt solution, sugar solution, milk, sea-water, air, sugarcane juice, soft drinks, sharbat, jaggery (gud), rocks, minerals, petroleum, LPG, biogas, tap water, tea, coffee, paint,wood, soil and bricks. A mixture may be homogeneous or heterogeneous. A mixture can be separated into other kinds of matter by physical processes. A mixture docs not have a fixed composition or a fixed melting point and boiling point. Most of the matter around us exists as mixtures of two or more pure substances.
From the above discussion we conclude that on the basis of their properties, all the matter can be divided into three general classes : elements, compounds and mixtures. A schematic representation of the different types of matter is given below.
We will now discuss the three types of matter, elements, compounds and mixtures, in detail.
Before we discuss elements, we should know the meaning of three terms which are used in distinguishing metal elements from non-metal elements. These are malleability, ductility and brittleness.
(i) The property which allows the metals to be hammered (or beaten) into thin sheets (without breaking),is called malleability.
(ii) The property which allows the metals to be drawn (or stretched) into thin wires (without breaking) is called ductility.
(iii) The property due to which non-metals break into pieces on hammering, is called brittleness. Brittleness is the opposite of malleability and ductility.
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Matter in Our Surroundings - Notes
2. 7. Metals are Solids at the Room Temperature
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5. 3. Non-Metals are Bad Conductors of Heat and Electricity.
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9. 7. Non-Metals may be Solid, Liquid or Gases at the Room Temperature.
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10. 11. Non-Metals Have Many Different Colours.
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15. 8. Metals Generally Have High Melting Points and Boiling Points.
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19. 8. Non-Metals Have Comparatively Low Melting Points and Boiling Points
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23. 1. Non-Metals are Not Malleable. Non-Metals are Brittle.
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24. To Study the Properties of a Suspension
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25. Effect of Temperature and Pressure on Solubility
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26. Chemical Formula for daily use material
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28. Pure Substances : Elements and Compounds
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33. 1. Separation by a Suitable Solvent
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34. Solutions, Suspensions And Colloids
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37. 3. Metals are Good Conductors of Heat and Electricity.
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39. 4. Non-Metals are Not Lustrous (Not Shiny). They are Dull in Appearance.
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