¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th sub- sci.&tech. Understanding Matter

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th sub- sci.&tech. Understanding Matter

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th sub- sci.&tech. Understanding Matter

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th sub- sci.&tech. Most of the matter around us exists as mixtures of two or more substances. Example : Sodium chloride is made up of Sodium and Chlorine. A pure substance consists of a single type of Particles. Example : Each and every particle of Nitrogen is made up of Nitrogen itself. Understanding Matter

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th sub- sci.&tech. An element cannot be further subdivided into simpler substances by any physical and chemical means. Today, 119 elements are known; out of which 92 are found in nature. Understanding Matter

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th sub- sci.&tech. An element can be represented by using a symbol. You already know that the symbol of Hydrogen is H. The molecular of Hydrogen consists of two hydrogen atoms. Hence the molecular formula of Hydrogen is written as H 2. ELEMENTS They are further classified into METALS NON- METALS METALLOIDS Understanding Matter

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th sub- sci.&tech. ElementsLustreSolid/liquid/gasHardBrittleDuctileMalleable Conductor of electricity CopperYesSolidYesNoYes IronYesSolidYesNoYes SilverYesSolidYesNoYes SulphurNoSolidNoYesNo NitrogenNogasNoYesNo SiliconYesSolidYesNoYes GermaniumYesSolidYesNoYes Table Understanding Matter

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th sub- sci.&tech. They are generally solids with characteristics such as hardness, malleability, Ductility, lustre and ability to conduct heat and electricity. Example : Copper, Iron, Silver etc. They are generally non-lustrous, brittle, poor conductors of heat and electricity. Example : Sulphur, Nitrogen etc. Metalloids have characteristics common to metals and non-metals. Example : Arsenic, Silicon, Selenium etc. Understanding Matter

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th sub- sci.&tech. A compound can be further subdivided into simpler substances by only chemical means. An example of a compound is water. It is a compound that contains the elements hydrogen and oxygen whose atoms are combined in the ratio 2 : 1. A compound has totally new properties then the constituents. The chemical formula H 2 O represents the compound of water. Water has different properties than Hydrogen and Oxygen. Understanding Matter

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th sub- sci.&tech. CompoundMolecular formula 1. WaterH2OH2O 2. Aluminium oxideAl 2 O 3 3. Potassium permanganateKMnO 4 4. Copper SulphateCuSO 4 5. Potassium dichromateK 2 Cr 2 O 7 6. Calcium hydroxideCa(OH) 2 7. Sodium bi carbonateNaHCO 3 8. Sodium carbonateNa 2 CO 3 9. BenzeneC6H6C6H6 10. Hydrogen sulphateH 2 SO 4 Understanding Matter

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th sub- sci.&tech. The constituents of a mixture retain their original properties. The mixture can be further subdivided into simpler substances by simple physical processes like holding the magnet, handpicking etc. In a mixture, the constituents are not in a fixed proportion. Understanding Matter

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th sub- sci.&tech. Example : Stainless steel is an alloy of iron, carbon, chromium and nickel. Carbon gives hardness to the mixture. Chromium and nickel give a silvery look to the mixture. In air there are mainly Nitrogen and Oxygen along with other gases. These gases retain their original properties. They do not chemically combine with each other on their own. Air is also a mixture. Understanding Matter

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th sub- sci.&tech. 1.Homogeneous mixture: The constituents of a homogeneous mixture are uniformly mixed throughout the mixture. The properties and composition of a homogeneous mixtures are the same throughout the mixture. Example : Potassium Permanganate solution is a homogeneous mixtures. 2.Heterogeneous mixture : The constituents of a heterogeneous mixture are not uniformly mixed throughout the mixture. The properties and composition of a heterogeneous mixtures are not the same throughout the mixture. Example : A mixture of water and oil is heterogeneous in nature. Understanding Matter

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th sub- sci.&tech. A solution is a homogeneous mixture of two or more substances. Lemonade, soda, water are some of the examples of solution. There are solid solutions (Alloys) and gaseous (air) also. The particles in a solution are very small size, they do not scatter a beam of light passing through it. Understanding Matter

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th sub- sci.&tech. Types of solutionsExamples Gas in liquidOxygen in water. Liquid in liquidAlcoholic beverages are basically solutions of ethanol in in water. Solid in liquidSugar or salt in water. Gas in solidSponge Liquid in solidMercury in gold, forming an amalgam. Solid in solidAlloys like steel, bronze and many others. Understanding Matter

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th sub- sci.&tech. The substances which dissolves is called the solute. The substances in which solute dissolves is solvent. In solutions the proportion of solute is less than that of solvent. A suspension is a heterogeneous mixture in which the solute particles do not dissolve but remain suspended in it. These particles are visible to the naked eye. A colloid is a mixture where the size of the particles is less than the size of particles in a suspension. Understanding Matter

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th sub- sci.&tech. Here milk is the dispersed phase and water is the dispersion medium. Here both the dispersed phase and dispersion medium are liquids. We cannot see colloidal particles with naked eyes. These small particles can easily scatter the beam of light. The scattering of beam of light is the Tyndall Effect. (Named after the scientist-Tyndall) Due to the relatively smaller size of the colloidal, as compared to the suspension, the colloidal mixture appears to be homogeneous. But a colloid mixture is a heterogeneous mixture. The two components of a colloid are the dispersed phase and dispersed medium E.g. milk. John Tyndall Understanding Matter

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th sub- sci.&tech. The tyndall Effect is caused by scattering of light by very small particles in colloidal solutions in a transparent medium. It is often observed from the dust in the air when sunlight comes in through a window, or comes down through holes in clouds. It is observed when headlight beams are visible on foggy nights. Understanding Matter

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th Sub- sci.&tech. Heterogeneous mixture can be easily separated by simple means like hand picking, filtration and other physical means. Evaporation is another technique used for separating mixtures. For some mixtures, one needs techniques like distillation and crystallization to separate them. Fractional distillation is another method where a mixture of liquids is separated into components according to their different boiling points. This method is also used for separate components of air. Understanding Matter

¸üµÖŸÖ ×¿ÖÖÖ ÃÖÓãÖÖ, ú´ÖÔ¾Ö߸ü ×¾ÖªÖ¯ÖϲÖÖê׬֭Öß, ´Ö¬µÖ ×¾Ö³Ö֐Ö, ÃÖÖŸÖÖ¸üÖ Std- 9 th Sub- sci.&tech. Understanding Matter