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STRUCTURE OF AN ATOM

STRUCTURE OF AN ATOM. STRUCTURE OF AN ATOM. ELECTRON - the NEGATIVE particles surrounding the nucleus of an atom. discovered by JOSEPH JOHN THOMPSON. STRUCTURE OF AN ATOM. PROTON – positively charged particle in the nucleus of the atom Discovered by Eugene Goldstein. STRUCTURE OF AN ATOM.

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STRUCTURE OF AN ATOM

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  1. STRUCTURE OF AN ATOM

  2. STRUCTURE OF AN ATOM • ELECTRON - the NEGATIVE particles surrounding the nucleus of an atom. • discovered by JOSEPH JOHN THOMPSON

  3. STRUCTURE OF AN ATOM • PROTON – positively charged particle in the nucleus of the atom • Discovered by Eugene Goldstein

  4. STRUCTURE OF AN ATOM NEUTRON – a neutral subatomic particle present in the nucleus of an atom Discovered by James Chadwick in 1932

  5. Electron Cloud Model

  6. DALTON’S ATOMIC THEORY has the following postulates. 1) Matter is made up of extremely small indestructible particles called atoms. 2) All atoms of a given element are alike John Dalton – English chemist that proposed the first atomic theory in 1803

  7. DALTON’S ATOMIC THEORY has the following postulates. 3) Atoms enter into combination with other atoms to form compounds, but remain unchanged during ordinary chemical reactions. 4) Atoms can combine in simple numerical ratios such as 1:1, 1:2, 2:3 and so on. Dalton’s Atomic Model

  8. Dalton’s atomic theory gives sufficient explanation to the Three Laws of Chemical Combination. Law of Conservation of Mass There is no detectable change in the masses of substances before and after the course of an ordinary chemical reaction. Mass is conserved. Dalton’s 3rd postulate

  9. Laws of Chemical Combination explains mass relationships in chemical reactions. Law of Definite Proportions or composition. A pure compound always contains the same elements combined in the same proportions or percentage by mass. % C = Mass of C / mass of CO2 x 100 % O = Mass of O/ mass of CO2 x 100 Dalton’s 2nd and 3rd postulate

  10. Laws of Chemical Combination explains mass relationships in chemical reactions. Law of Multiple Proportions When two elements combine to form more than one compound, the masses of one element which combine with a fixed mass of the other element are in a ratio of SMALL whole numbers • H2O (water) • H2O2 (Hydrogen peroxide) • Mass O = 16 g • Mass of H = 1 g • Since the • Atom of oxygen always has the same mass • Ratio = 2:1

  11. Sample Atomic Structure Hydrogen: a proton surrounded by an electron cloud A Hydrogen Atom

  12. 35 Cl 17

  13. Hydrogen Atomic Mass = 1 Atomic Number = 1 Deuterium  Atomic Mass = 2  Atomic Number = 1 Two isotopes of hydrogen

  14. References • http://dbhs.wvusd.k12.ca.us/AtomicStructure/AtomicStructure.html • http://web.jjay.cuny.edu/~acarpi/NSC/3-atoms.htm

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