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Thales (600 B.C.)

Thales (600 B.C.). Water. Xenophanes (500 B.C.). Earth. Water. Empedocles (440 B.C.) Four elements. Earth. (more commonly called dirt). Water. Fire. Air. Two Forces shape matter. Love & Strife. Democritus Athens, Greece 400 B.C.

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Thales (600 B.C.)

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  1. Thales (600 B.C.) Water

  2. Xenophanes (500 B.C.) Earth Water

  3. Empedocles (440 B.C.)Four elements Earth (more commonly called dirt) Water Fire Air

  4. Two Forces shape matter Love & Strife

  5. Democritus Athens, Greece 400 B.C.

  6. The smallest particles of matter are indivisible. Since atomos is the Greek word for “indivisible” I shall call these particles “atoms”. “Atoms” cannot be destroyed, so there is conservation of matter.

  7. Aristotle Athens, Greece 340 B.C. Aristotle studied under Plato who also had opinions on chemistry. However, Aristotle had the most influence on the history of chemistry. Besides chemistry, he also tackled physics, biology, psychology, and logic.

  8. It’s ironic that the theories of Aristotle which were most accepted were also the most incorrect. For example, he proposed and embraced the mystical fifth element. It took chemists 2,000 years to recognize that there was no mystical fifth element. His theories that were most correct were mostly ignored. For example, he correctly classified dolphins as mammals and not fish. It took 2,000 years for biologists to accept this.

  9. First Table of the Elements Dry Hot Cold Wet

  10. Fifth Element • Quintessence • Philosopher’s stone

  11. Fifth Element makes up the celestial bodies Gold is the perfect metal.All other metals are less perfect. The fifth element is so divine that it can turn the lesser (more base) metals into gold.

  12. Fifth Element Elixir of life (a fountain of youth)

  13. Disagree with Democritus • Matter does not consist of atoms • Democritus said atoms cannot be divided. You cannot place restraints on the gods.

  14. Antoine Laurent Lavoisier France 1793 • Lavoisier has been called the father of modern chemistry. • Started a system of chemical nomenclature that used ide, -ic & -ous endings. Examples: Sodium chloride, Ferric oxide and Ferrous oxide

  15. Antoine married the daughter of the tax collector, which helped him pay for his expensive laboratory. Marie acted as a skilled lab assistant, translator of English science publications, and illustrator for Lavoisier’s experiments

  16. 15 Lavoisier • When heated mercury turned red and absorbed 1/5 of the air. • The amount of “active air” consumed was the same as the amount of “active air” released later.

  17. non-active Air Room Air Active Air generate acids Sulfuric acid Died quickly Lived longer Lived for a while Oxygen Azote S + O2 SO2 2SO2 + O2  2 SO3 SO3 + H2O  H2SO4

  18. Table of the Elements (33) Antimony Arsenic Bismuth Cobalt Copper Gold Iron Lead Manganese Mercury Molybdena Nickel Platina Silver Tin Tungstein Zinc Lime Magnesia Barytes Argill Silex • Oxygen • Azote • Hydrogen • Sulphur • Phosphorus • Charcoal • Muriatic radical • Fluoric radical • Boracic radical Argill (clay or alum=potassium aluminum sulfate) Silex (silicon dioxide = quartz Magnesia (epsom salts=magnesium sulfate) Lime = calcium oxide

  19. John Dalton England 1796

  20. Elements are composed of minute, indivisible particles called atoms

  21. 4. Chemical compounds are formed by the union of two or more atoms of different elements.

  22. Arranged from light to heavy by their relative weights Dalton’s Elements

  23. Johan Jacob Berzelius from Sweden

  24. Berzelius’ Symbols for Elements • Older elements take the symbol from their Latin name. • Fe comes from ferrum not iron. • Instead of G for gold he wants Au from aurum. • Instead of S for Silver he wants Ag from argentum. • Newer symbols come from English names. • O comes from oxygen. • 2000 experiments over a ten-year period to determine accurate atomic masses for all the elements now known.

  25. John Newlands England 1867 Researchers had already began to arrange and classify elements: Metals vs. non-metals In tables of increasing atomic weight John Newlands from England had a different way to arrange elements.

  26. Certain elements resembled one another in behavior. • Chlorine, bromine & iodine • violently corrosive • form acids • Lithium, sodium, potassium • Unite violently with oxygen or water • Oxides form caustic aqueous solutions Every eighth element have similar characteristics Li Be B C N O F Na Mg Al Si P S Cl K Ca ? ? As Se Br I call this the “Law of Octaves”

  27. “Law of Octaves” He presented his theory to the England Chemical Society and was laughed at. They said to arrange it alphabetically.

  28. Dmitri Ivanovich Mendeleev Russia 1871

  29. Periodic Law Like Newlands, he used the lithium, sodium, and potassium plus the chlorine family as guide posts He also saw a periodic repeating of characteristics. However on the third period, he thought there were more than the seven elements that Newlands listed.

  30. Gallium Germanium

  31. Periodic Table of the Elements The elements are ordered by the number of protons they have in their nucleus Atomic Number

  32. Periodic Table of the Elements Elements are listed by increasing mass. But grouped by reoccuring properties

  33. WHERE DID THE ELEMENTS COME FROM?

  34. End

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