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Honors Chem 3.3 & 21

Democtritus 400 BC- atom concept
George Bauer 1500s ore
Philippus Theophrastus Bombastras von Hohenheim 1500s medicine
Berzelius late 1700s (alchemy) symbols for elements
George Stahl 1600 phlogiston
Antoine Lavoisier 1700 oxygen and LOCOM (conservation of mass)
Proust 1700 LODP (def. proportions)
Dalton 1800 LOMP (multiple proportions). Atomic theory.
Thomson 1900. CRT tubes. Discovered electrons. Determined electron had mass, - charge and in all matter.
Robert Millikan 1904. found exact charge & mass of an electron. Electron is 1/1837 of a hydrogen atom.
Thomson's model cookie dough, plum pudding.
Rutherford alpha particle @ gold foil. Nucleus small, but has all mass. Most of atom = empty space.
Henri Becquerel Discovered uranium. 1st to describe radioactivity.
Marie Curie discovered Radium and radioactive elements.
Atomic # Z (# of protons)
Atomic Mass # A (protons and neutrons)
atomic mass unit amu
p+, n*, e- protons, neutrons, electrons
mole 6.022x10^23
Avogadro's # 6.022x10^23
nucleon protons and neutrons
nuclide atom; identified by # of protons and neutrons. Ex: 228:88 Ra or Radium-228.
Ratio of neutrons:protons in low atomic # elements 1:1
Ratio in larger atomic # elements 1.5:1
2, 8, 20, 28, 50, 82, 126 magic cuz stable combination in dif nuclear shells
Alpha particle 2 protons and neutrons bound together (4:2 He)
Gamma rays released in order to make nucleus more stable
Roentgen 2*10^9 ion pairs passing through 1 cm^3 of dry air.
Rem dose of type of ionizing radiation; radiation effect on human tissue.
Created by: Broods



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