1. Chemistry II Atomic Theory History Tutorial

2. Time Periods 500 BC – 1600 AD: The Alchemical Era 1600 AD – 1800 AD: The Transitional Time Period 1800 AD – 1900 AD: Dalton’s Atom 1900 AD – Present: The Quantum Era

3. Alchemical Era: 500 BC – 1600 AD Democritus ~ 450 BC: He is the originator of the term, “Atomos”, meaning indivisible.Democritus Empedocles ~ 400 BC: He is the originator of the Four Element Theory, Earth, Air, Fire, and Water. Aristotle ~ 350 BC: He added to the Four Element Theory that matter has the properties of hot, cold, dry, and wet.Aristotle

4. Transitional Time Period: 1600 - 1800 Robert Boyle – 1661: He publishes the book The Skeptical Chemist, which disproves the four element theory.Robert Boyle Antoine Lavoisier – 1770’s: His greatest contributions were the co-discovery of oxygen, gunpowder manufacture, and law of conservation of mass.Antoine Lavoisier Sir Isaac Newton – 1642 – 1727: He freed science from “Godlessness” as it was thought of by the church.Sir Isaac Newton

5. Other Key Transitional Scientists Galileo Galilei – 1564 - 1642Galileo Galilei Charles Augustin de Coulomb – 1736 – 1806Charles Augustin de Coulomb Phlogiston Theory: The theory that fire is caused by the release of a substance called “phlogiston”Phlogiston Theory Joseph Priestly – 1733 - 1804Joseph Priestly

6. 1800 AD – 1900 AD: Dalton’s Atom John Dalton – 1803: Dalton’s atomic theory reverts back to DemocritusJohn Dalton –Matter is composed of small, indivisible particles called atoms –The atoms of a given element are identical –The law of definite composition –Compounds are created by atoms bonding through chemical reactions

7. More Dalton era chemists Amadeo Avogadro – 1809: He worked with gases and confirmed Dalton’s theory.Amadeo Avogadro Dmitri Mendeleev – 1866: He arranged the elements into groups in the first periodic table.Dmitri Mendeleev Joseph Louis Gay-Lussac – 1802: He also worked with gases and has a funny name.Joseph Louis Gay-Lussac

8. 1900 AD – Present: The Quantum Era The discovery of Sub-atomic particles –Cathode Rays – the electron was the first sub-atomic particle discovered by Crookes and ThomsonCrookesThomson –Rutherford’s Gold Foil Experiment: He learned that atoms contain a dense, positively charged nucleus, due to protons in nucleusRutherford’s Gold Foil Experiment –James Chadwick discovers the neutronJames Chadwick Neils Bohr – Modifies the atomic model once again.Neils Bohr

9. Radioactivity X-Rays were first discovered by Wilhelm Roentgen (Nobel site)Wilhelm RoentgenNobel site Henri Becquerel accidentally discovered radiationHenri Becquerel Marie Curie discovered various radioactive elementsMarie Curie Ernest Rutherford defines radiation as Alpha (  ), Beta (  ), and Gamma (  ) raysErnest Rutherford

10. Manhattan Project Began in the 1940’s as a race to produce the first atomic weapon to end WWII first atomic weapon Directed by American, J. Robert Oppenheimer, who studied under ThomsonJ. Robert Oppenheimer Enrico Fermi constructed the first nuclear pile (for a controlled nuclear reaction)Enrico Fermi Albert Einstein started Roosevelt on the projectAlbert Einstein Three labs: Hanford, Los Alamos, and Oak RidgeHanfordLos AlamosOak Ridge

11. Quantum Chemistry Max Plank wins the Nobel Prize in 1918 for his theory of the wave-particle duality.Max Plank In 1925, Erwin Schrodinger proposed an equation to describe the shapes of orbitals in an atom.Erwin Schrodinger equation Werner Heisenberg supports Schrodinger with is Uncertainty Principle.Werner Heisenberg Quantum theory now begins to meld into the area of physics

12. What’s Next First you must master the history of the atom Then we will learn about the work of Mendeleev and Seaborg on the periodic table After that, we will begin to put atoms together to form molecules Enjoy