Chy102-Lecture 02 - D ne o General Chemistry Chem102 for Engineering Dr Raafat Aly nd 2 Lecture Objectives Atomic theories and the definition of

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General Chemistry Chem102 for Engineering Dr. Raafat Aly 2 nd Lecture 31/10/2007 Done
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2 Objectives Atomic theories and the definition of atom. Law of conservation of mass Law of definite proportions Law of multiple proportions Identify the components of the atom. Define the term isotope. Explain the nuclear stability. Identify the main features of the periodic table. Identify metals and non metals. Write nuclear symbols of ions. What are molecules and ions?
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3 Atoms and the atomic theory In 1808, an English scientist , John Dalton, developed the atomic model of matter which suggests the following: 1. An element is composed of tiny particles called atoms . 1. Atoms of the same element show the same properties while atoms of different elements show different properties. 1. Compounds are formed when atoms of two or more elements combine. A given compound always has the same number and type of atoms . 1. In an ordinary chemical reaction, atoms move from one substance to another but no atom of any element disappears or is changed into an atom of another element .
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4 Some important laws Law of conservation of mass This states that there is no detectable change in mass in ordinary chemical reaction. (Postulate 4). "Mass is neither created nor destroyed" Example: If you start with 10 g of reactants, so you will definitely get 10 g of products (mass of reactants = mass of products) Law of constant composition (law of definite proportions) A compound always contains the same elements in the same proportions by mass [same composition] (Postulate 3). Example: CuCO 3 Cu : O : C 51% : 39% : 10% (by mass) Dalton Atomic theory explained three of the basic laws of chemistry
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5 Law of multiple proportions When two elements form a series of compounds, the ratios of the masses of one element that combine with 1 gram ( or any other fixed mass ) of the second element can be reduced to a ratio of small whole numbers small whole numbers (postulate 3).
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This note was uploaded on 12/13/2010 for the course CHEM 102 taught by Professor Raafat during the Spring '10 term at Ain Shams University.

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Chy102-Lecture 02 - D ne o General Chemistry Chem102 for Engineering Dr Raafat Aly nd 2 Lecture Objectives Atomic theories and the definition of

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