ChE102_Notes_-_Chap_1 - ChE102 Div 9 & 10 Fall 2009...

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Fall 2009 CHAPTER 1 – Introduction to Chemistry Petrucci: 1.4-1.5, 2.7-2.8, 3.1-3.3 Note that this is not a comprehensive introduction but rather highlights the minimum required background for the course. If any of the information here is not familiar to you, read the sections in the textbook. If you require more assistance, please contact your instructor or the TAs. Dalton’s Atomic Theory: An atom is a minute, indivisible particle that is the smallest unit of a chemical element. Atoms are neither created nor destroyed in chemical reactions. For a given element, atoms have the same properties For atoms of different elements, these properties vary Atoms combine in fixed proportions to form compounds Physical VS Chemical Change Physical Change o Sample may go from a liquid, to a solid, or to a vapour, or to some combination thereof o Chemical make-up unchanged Chemical Change or Reaction o A change in composition occurs o Atoms are added to or lost from the initial sample Law of Conservation of Mass: o The total mass of substances present before a chemical reaction is the same as the total mass after the reaction. Compounds and Molecules A molecule is the smallest unit that has the same proportion of elements as the overall compound o For example: a water molecule (H 2 O) is composed of two hydrogen atoms (H) and one oxygen atom (O) Table salt is sodium chloride: o Formula NaCl (the ratio of sodium to chlorine is 1:1) but it is not possible to identify a molecule of sodium chloride Law of Constant Composition: o All samples of a compound have the same proportion by mass of the constituent elements. Chapter 1
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This note was uploaded on 12/15/2009 for the course ENGINEERIN CHE 102 taught by Professor Soares during the Fall '09 term at Waterloo.

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ChE102_Notes_-_Chap_1 - ChE102 Div 9 & 10 Fall 2009...

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