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  1. Everything What is Everything Made of? MPL1203

  2. What is everything (Matter)made of? Greek Mythology –Fire, Air, Water, Earth • Leucippius (Born-50BCE) Democritus (Born –460 BCE) Postulated an indivisible form of matter THE ATOM Early Postulates Aristotle in “Metaphysics”----- The shape and existence of all things are determined by void and atoms through the differences in shape, position and arrangement of the atoms and the proportion of void in the substance.

  3. What is An Atom Made Of?(First Approximation) Electron(s) Nucleus Proton Neutron(s)

  4. Discovery of the Electron Electrons Missing Target Electrons Hitting Target 1897 J.J. Thompson 1899 Charge of the Electron Measured Crookes Tube Vacuum Tube

  5. Electrons, Electricity??? Electricity was thought of as a stream, (analogous to water flowing as a pipe) Now thought of as a the motion of Discrete Particles having mass (Electrons) Carrying the smallest possible unit of charge

  6. The Plum Pudding Model J.J. Thompson- 1904 Electrons (Negativly Charged) Field (Positively Charged) In Today's Vernacular- The Chocolate Chip Model

  7. Discovery of the Nucleus Earnest Rutherford-1911 Rutherford called it a“Central Charge (1920 called it a Proton)

  8. The Atom has No Charge Number of Protons = Number of Electrons Bohr,s Model 1913 – Atomic Model with Fixed Orbits proposed – Modeled after the Solar System Protons Electrons Inner Orbit Nucleus Outer Orbit Nucleus

  9. What Did Bohr’s Model Accomplish ? Stability Electrical Forces balanced by Centrifugal Forces Identity Change in number of Protons/Electrons Changes the Element Regeneration Once Pulled Apart, the Atom Reforms as before

  10. How Big is It, (Are They)? 1 Proton ( or Neutron)----1.67 x10-24 Grams =0.000000000000000000000001.67 Grams 1 electron-----9.1x10-28 Grams =0.0000000000000000000000000009.1Grams The Proton weighs 1800 x the Electron The Atom is about 5 X 10-8 Cm

  11. Lets Try Analogies If the Nucleus were the size of a Garbage Can The Atom would be the size of LA If an electrons weighed as much as a watermelon The proton would weigh as much as an elephant Conclusion; It’s mostly nothing

  12. Strange Things were Happening Sometimes the nucleus of an element weighed differently than another nucleus of the same element Rutherford – 1920 Postulated a Neutron Doublet Irene and Fredrick Joliot- Curie 1932 found radiation they thought was protons James Chadwick Didn’t Believe It

  13. Discovery of the Neutron James Chadwick - 1935 A Unique Particle, (not an electron or a proton ) Essentially the same mass as an Proton Has no Charge With the Proton, Makes up the Nucleus

  14. Bohr Model of Hydrogen and Helium

  15. Bohr Model of Potassium(K) and Uranium (U) 235U92 39P19 238U92 92 Protons 143 Neutrons Atomic Mass = 235 92 Protons 146 Neutrons Atomic Mass=238 19 Protons 20 Neutrons Atomic Mass=39

  16. So Little From So Much • Marie Curie purified 10,000,000 grams of Pitchblende to get 0.1 Grams of Uranium • Natural uranium is • 99. 3%U238 • 0. 7% U235 (The Bomb Type)

  17. . Combine the Uranium(s) with Fluorine to get a gas (Uranium Hexafluoride) Pass the gas through a porous filter – More 235U based gas than 238U gas gets through. Collect it and do it again,& again & again, & again, & again------ Centrifuge the Gasses- Heavier 238U based gas separates from lighter 235 U based gas Collect it and do it again,& again 7 again, & again, & again--------- Problem – Not Enough 235U How to increase the Concentration? Thermal Diffusion- Used Heated, Pressurized Uranium Hexafluoride

  18. How Big was the Job? Oak Ridge Pop. 75,000 $ 17 Billion (approx $ today)

  19. New Term—Electron Volt (ev)A Measure of Energy Chemical Reaction-Dynamite Releases 1 ev per Atom Nuclear Reaction – ( The Bomb) Releases 1,000,000 ev per atom So Much from So Little

  20. They like Things Orderly Ti=50 Zr=90 ?=180 V=51 Nb=94 Ta=182 Cr=52 Mo=96 W=186 Mn=55 Rh=104,4 Pt=197,4 Fe=56 Ru=104,4 Ir=198 Ni=Co=59 Pd=106,6 Os=199 H=1 Cu=63,4 Ag=108 Hg=200 Be=9,4 Mg=24 Zn=65,2 Cd=112 B=11 Al=27,4 ?=68 Ur=116 Au=197? C=12 Si=28 ?=70 Sn=118 N=14 P=31 As=75 Sb=122 Bi=210? O=16 S=32 Se=79,4 Te=128? F=19 Cl=35,5 Br=80 J=127 Li=7 Na=23 K=39 Rb=85,4 Cs=133 Tl=204 Ca=40 Sr=87,6 Ba=137 Pb=207 ?=45 Ce=92 ?Er=56 La=94 ?Yt=60 Di=95 ?In=75,6 Th=118? How we organize these different Elements??? Mendeleev 1869 Are there Common Characteristics ??? Original Table – 63 Elements

  21. Periodic TableOf The Elements

  22. Families Alkali Metals Noble Gasses Alkaline Earth Trans Uranic

  23. The End

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