121lec1 - Chemistry 121 Chapter 1 Study material for this...

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Chemistry 121 Chapter 1 INTRODUCTION: MATTER AND MEASUREMENT 1.1 The Study of Chemistry Matter – physical material of the universe – has mass and occupies space About 100 basic elements combine to form all matter. Atoms – infinitesimally small building blocks of matter. Atoms combine to form molecules which are held together in specific shapes. Atoms are represented as colored spheres (Fig. 1.1 in text) to form compounds such as: o Oxygen o Water o Carbon dioxide o Ethanol – grain alcohol – alcohol in beverages such as beer and wine o Ethylene glycol – viscous liquid used in antifreeze mixtures All changes such as the boiling of water to changes in our bodies to combat viruses can be explained in the unobservable world of atoms and molecules. Macroscopic realm (macro = large) and submicroscopic realm of molecules (very small – mostly unobservable by the eye) Why Study Chemistry? Chemistry – central science Chemistry – powerful language and ideas to understand and describe matter. 1 Study material for this chapter Textbook sections 1.1 through 1.6 These lecture notes should be used as a guide for the textbook only.
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Chemistry and the Chemical Industry o Fig. 1.3 in text for common supermarket products o Table 1.1 in text – top 10 chemicals produced by the Chemical Industry in 1997 Classification of Matter States of matter o Gas (vapor) – Fig. 1.4 in text – no fixed volume or shape - conforms to volume of container – can be compressed to occupy smaller volume – can be expanded to occupy larger volume o Liquid – Fig. 1.4 in text – has a distinct volume – no shape – assumes shape of container o Solid – Fig. 1.4 in text – has both a definite shape and volume – is rigid o Solids and liquids cannot be compressed to an appreciable extent o Gas – molecules far apart – moving at high speeds o Liquids – molecules packed closer together but still move rapidly allowing molecules to slide over each other – liquids pore easily o Solids – molecules are held tightly together – usually definite arrangements – rigid shapes Pure Substances or Mixtures Pure substances – fixed composition and distinct properties – e.g water and sodium chloride (NaCl) – primary substances of sea water Pure substances o Elements that cannot be decomposed into simpler units – consisting of one atom only (Fig. 1.5(a)) o Molecules of an element such as O 2 and H 2 (Fig. 1.5(b)) o Compounds – composed of 2 or more elements – contain two or more atoms 2
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Mixtures – combinations of 2 or more substances in which each substance retains its own chemical identity and properties (Fig.1.8). Mixtures are characterized by the following: o Variable composition – e.g. table salt in water, copper sulfate in water (Fig. 1.8) o Heterogeneous mixtures – do not have uniform properties, composition and appearance, e.g. pepperoni pizza o
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This note was uploaded on 05/14/2009 for the course CHEM 121 taught by Professor Wyzlouzil during the Fall '07 term at Ohio State.

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121lec1 - Chemistry 121 Chapter 1 Study material for this...

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