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Unformatted text preview: I. Three Important Laws a. Law of conservation of mass (Lavoisier)- Mass is neither created nor destroyed b. Law of definite proportion (Proust) - A given compound always contains exactly the same proportion of elements by mass. c. Law of multiple proportions (Dalton)-When two elements form a series of compounds, the ratios of the masses of the second element that combine with 1 gram of the first element can always be reduced to small whole numbers. i. Dalton’s Atomic Theory: 1. Each element is made up of tiny particles called atoms. 2. The atoms of a given element are identical; the atoms of different elements are different in some fundamental way or ways. 3. Chemical compounds are formed when atoms of different elements combine with each other. A given compound always has the same relative numbers and types of atoms. 4. Chemical reactions involve reorganization of the atoms- changes in the way they are bound together. The atoms themselves are not change in a chemical reaction. I I. People a. Robert Millikan i. Preformed experiments involving charged oil drops to determine the magnitude of the charge on a single electron. ii. Calculated the mass of the electron: 1.06x 10-19 g b. J.J. Thomson i. Postulated the existence of electrons using cathode-ray tubes to determine the charge-to-mass ratio of an electron. ii. The atom must also contain positive particles that balance exactly the negative charge carried by particles that we now call electrons. : 5.60 10-9 g/c c. Ernest Rutherford i. Explained the nuclear atom—atom has a dense center of positive charge called the nucleus. ii. Electrons travel around the nucleus at a relatively large distance. I I I.Things inside of an Atomic Structure a. Electrons- outside the nucleus—negative b. Protons- inside the nucleus—positive charge c. Neutrons- inside the nucleus- no charge d. Isotopes i. Atoms with the same number of protons but different numbers of neutrons ii. Show almost identical chemical properties; chemistry of atom is due to its electrons iii. In nature most elements contain mixtures of isotopes IV. Chemical Bonds a. Ionic bonds i. Bonds form due to force of attraction between oppositely charges ions.Bonds form due to force of attraction between oppositely charges ions....
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This note was uploaded on 04/06/2010 for the course CMS hgkh787y taught by Professor Uiuy during the Spring '10 term at École Normale Supérieure.
- Spring '10