# Lesson 2_ Structure and Properties of Matter.PDF -...

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Structure and Properties of Matter : 25 :2Structure and Properties of MatterAll the objects around us whether living or non-living are matter. Water we drink, food weeat, air we breathe, chair we sit on, are all examples of matter. Matter is anything thathas mass and takes up space.Matter appears in a huge variety of forms such as rocks,trees, computer, clouds, people, etc.Matter embraces each and everything around us.Therefore, in order to understand the world, it would be necessary to understand the matter.Each pure kind of matter is called substance.Here, pure we mean the same throughout. Thus, aluminium is one substance and water is another. Please remember, the scientificmeaning of substance is a little different from its every day meaning and we shall discussit a little later in this lesson.OBJECTIVESAfter completing this lesson, you will be able to:zdefine various states of matter as solid, liquid and gas, and distinguish one from theother based on their properties;zclassify the matter based on their composition as element, compound and mixture;zdifferentiate between atoms and molecules;zstate Dalton’s atomic theory and explain various laws of chemical combinations;zdefine isotopes, atomic mass and molecular mass;zexpress chemical reaction in form of a balanced chemical equation;zdefine mole concept and molar quantities such as molar mass and molar volume;zapply mole concept to a chemical reaction and show a quantitative relationship betweenmasses of reactants and products;zdefine Gay Lussac’s law of combining volume and Avogadro’s law;zsolve numerical problems based on various concepts covered above;2.1 CLASSIFICATION OF MATTEREarlier Indian and Greek philosophers and scientists attempted to classify the matter in theform of five elements - Air, Earth, Fire, Sky and Water.This classification was more ofphilosophical nature.In modern science, however, there are two main ways of classifyingthe matter :i)Based on physical states: All matter, at least in principle, can exist in three states,solid, liquid and gas.
: 26 : Structure and Properties of Matterii)Based on composition and properties: The classification of matter includes elements,compounds and mixtures.2.1.1 PHYSICAL STATE OF MATTERA given kind of matter may exist in different physical forms under different conditions.Water, for example, at one atmospheric pressure, may exist as solid, liquid or gas withchange of temperature. Sodium metal is normally solid, but it melts to a silvery liquidwhen heated to 98oC. Liquid sodium changes to a bluish gas if the temperature is raisedto883oC. Similarly, chlorine, which is normally a gas can exist as a yellow liquid or solidunder appropriate conditions. These three different forms of matter differ from each otherin their properties. Solids are rigid with definite shapes. Liquids are less rigid than solidsand are fluid, i.e. they are able to flow and take the shape of their containers. Like liquids,gases are fluids, but unlike liquid, they can expand indefinitely.

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