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Atomic Theory

Atomic Theory. History of the Discoveries Related to the Atom Mr. Addison. Timeline of Atomic Theory. 450 BC 1800’s _________________________________________________________. Democritus: matter was made of “atoms”.

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Atomic Theory

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  1. Atomic Theory History of the Discoveries Related to the Atom Mr. Addison

  2. Timeline of Atomic Theory 450 BC 1800’s _________________________________________________________ Democritus: matter was made of “atoms” Dalton: proposed 5 components to an Atomic Theory.

  3. Dalton’s Theory: Foundation of Future Investigations • All matter consists of tiny particles. • Atoms are indestructible and unchangeable. • Elements are characterized by the mass of their atoms. • When elements react, their atoms combine in simple, whole-number ratios. • When elements react, their atoms sometimes combine in more than one simple, whole-number ratio.

  4. Atomic Theory 1897-1920 ___________________________________ Planck quanta 1901 Bohr quantum model 1913 Rutherford nucleus 1911 Thompson negative charge in the atom 1897

  5. Contributions to Modern Atomic Theory De Broglie Wave nature of matter 1924 _____________________________________ Gell-Mann Quarks 1962 Heisenberg e- is a wave and a particle 1926 Schrodinger e- orbits as a wave 1926 Chadwick neutron 1932

  6. Experiments that Characterized Particles of the Atom • Thompson Cathode Ray tube: • Electrons are negative in charge • http://chemmovies.unl.edu/ChemAnime/CATHRAYD/CATHRAYD.html • Rutherford’s Gold Foil: • Nucleus contains protons and is very small/dense • http://www2.wwnorton.com/college/chemistry/gilbert/tutorials/ch3.htm • Bohr model: • Electrons travel in certain paths • http://chemmovies.unl.edu/ChemAnime/BOHRQD/BOHRQD.html

  7. 3 Basic Parts of the Atom.

  8. Particles of the Atom to date: • Nucleus • Protons = p+ = 3 quarks • Neutrons= n0 = 3 quarks • Electron Cloud • Electrons =e- (particle/wave) Held together by a force called : Gluon

  9. Types of Quarks Determine Chargehttp://nobelprize.org/educational_games/physics/matter/1.html Quarks = up (+2/3) and down (-1/3) p+ = 2ups and 1 downn0 = 2 down and 1 up +2 +2-1 = +1 -1-1+2 = 0 3 3 3 3 3 3 Gluon forces between quarks

  10. Predicting the Location of an Electron in an Atom: • Bohr proposed 4 characteristics to consider to predict the location of an electron. • l = the distance from the nucleus • m = the shape of the orbital in which the e- occupies. (s,p,d,f) • n = axis the orbital occupies. (x, y, z) • s =spin of the e- (+1/2 , -1/2)

  11. Distance from the nucleus: • Levels 1-7: When looking at the periodic table, can be determined by the period number. 1 2 3 4 5 6 7

  12. Shape of the Orbital on the x,y,z Axis • The number of electrons in a particular region determines the shape. s shape 2e- p shape 6e-

  13. Shape of the Orbital on the x,y,z Axis d shape 10e- f shape 14e-

  14. Atom with overlapping orbitals

  15. Spin of the Electron • http://www.colorado.edu/physics/2000/applets/a2.html

  16. Do Electrons behave as a particle or as wave? Definition of Light: • http://chemmovies.unl.edu/ChemAnime/DEFLITD/DEFLITD.html

  17. Einstein and Bohr Bohr: -Predictability Einstein: -causality

  18. Electrons travel in waves

  19. Electron behavior as it moves to other energy levels. • This emitted energy is equal to the difference between the high and low energy levels, and may be seen as light. Light emission tutorial http://www2.wwnorton.com/college/chemistry/gilbert/tutorials/ch3.htm

  20. Electrons are Particles / Photons • Electrons travel in discreet packets called photons. • To describe these unique packets or quantities of energy the term “quanta” is used. • Every element on the periodic table is made up of atoms with a unique signature of spectral lines

  21. Electrons exhibit particle and wave like behavior“Duality”

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