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Ch-1 : Matter in Our Surroundings (New)

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Metals and Non-Metals

Elements can be classified as metals, non-metals and metalloids on the basis of their physical and chemical properties.  Physical properties of metals: Lustre : Metals in their pure state have a shining surface called metallic lustre. Malleability : Metals are malleable i.e can be beaten into thin sheets. Note : Gold and silver are the most malleable metals. Ductility : The ability of metals to be drawn into thin wires is called ductility.  • Gold is the most ductile metal.  Note : 1 gramof gold can be drawn into a thin wire about 2km long because of their malleability and ductility. Conductivity : Metals are good conductors of heat and electricity • Silver and copper are good (best) conductors of heat and electricity.  • Lead and mercury are comparatively poor conductors of heat and electricity.  Sonorous : Metals are sonorous i.e they produce a sound when hit (strike) with a hard surface (object). • The metals that produce a sound on striking a hard surface a...

Chemical Reaction and Equation

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• Whenever a chemical change occurs, we can say that a chemical reaction takes place i.e Chemical reactions involve chemical changes. Chemical Change :   • If the identity, composition or nature of a chemical substance change and can not be reserved by any physical process, it is called chemical change . Chemical Reaction :   • The process involving a chemical change is called chemical reaction . • The process in which one or more substance as reactants gets converted (transformed) into new substances with new properties in product as a result of chemical change is called chemical reaction . Reactants :   • The substances that undergo chemical change or takes part in a chemical reaction is called reactants .  Products :   • The new substances produced (formed) during the reaction as a result of chemical change are called products . • Chemical reactions involves the breaking and making of bonds between atoms i.e in a chemical reaction old bonds are b...