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C H A P T E R11Intermolecular Forces and Liquidsand SolidsI N T R O D U C T I O NALTHOUGH WE LIVE IMMERSED IN THE MIXTURE OF GASES THAT MAKEUPEARTHS ATMOSPHERE,WE ARE MORE FAMILIAR WITH THE BEHAVIOROF LIQUIDS AND SOLIDS BECAUSE THEY ARE MORE VISIBLE. EVERY DAYWE USE WATER AND OTHER LIQUIDS FOR DRINKING,BATHING,CLEAN-ING,AND COOKING,AND WE HANDLE,SIT UPON,AND WEAR SOLIDS.MOLECULAR MOTION IS MORE RESTRICTED IN LIQUIDS THAN INGASES;AND IN SOLIDS,THE ATOMS AND MOLECULES ARE PACKED EVENMORE TIGHTLY TOGETHER. IN FACT,IN A SOLID THEY ARE HELD IN WELL-DEFINED POSITIONS AND ARE CAPABLE OF LITTLE FREE MOTION RELATIVETO ONE ANOTHER. IN THIS CHAPTER WE WILL EXAMINE THE STRUCTUREOF LIQUIDS AND SOLIDS AND DISCUSS SOME OF THE FUNDAMENTAL PROP-ERTIES OF THESE TWO STATES OF MATTER.11.1THE KINETIC MOLECULAR THEORY OFLIQUIDS AND SOLIDS11.2INTERMOLECULAR FORCES11.3PROPERTIES OF LIQUIDS11.4CRYSTAL STRUCTURE11.5X-RAY DIFFRACTION BY CRYSTALS11.6TYPES OF CRYSTALS11.7AMORPHOUS SOLIDS11.8PHASE CHANGES11.9PHASE DIAGRAMS417BackForwardMain MenuTOCStudy Guide TOCTextbook WebsiteMHHE Website
In Chapter 5 we used the kinetic molecular theory to explain the behavior of gases interms of the constant, random motion of gas molecules. In gases, the distances betweenmolecules are so great (compared with their diameters) that at ordinary temperaturesand pressures (say, 25°C and 1 atm), there is no appreciable interaction between themolecules. Because there is a great deal of empty space in a gas—that is, space thatis not occupied by molecules—gases can be readily compressed. The lack of strongforces between molecules also allows a gas to expand to fill the volume of its con-tainer. Furthermore, the large amount of empty space explains why gases have verylow densities under normal conditions.Liquids and solids are quite a different story. The principal difference between thecondensed states (liquids and solids) and the gaseous state is the distance between mol-ecules. In a liquid the molecules are so close together that there is very little emptyspace. Thus liquids are much more difficult to compress than gases, and they are alsomuch denser under normal conditions. Molecules in a liquid are held together by oneor more types of attractive forces, which will be discussed in the next section. A liq-uid also has a definite volume, since molecules in a liquid do not break away from theattractive forces. The molecules can, however, move past one another freely, and so aliquid can flow, can be poured, and assumes the shape of its container.In a solid, molecules are held rigidly in position with virtually no freedom of mo-tion. Many solids are characterized by long-range order; that is, the molecules arearranged in regular configurations in three dimensions. There is even less empty spacein a solid than in a liquid. Thus solids are almost incompressible and possess definite

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Term
Fall
Professor
NoProfessor
Tags
Atom, Hydrogen Bond, Intermolecular force

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