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1700 BCE
King Hammurabi's reign over Babylon
Knew metals were being recorded and listed in the conjunction with heavenly bodies -
1520 BCE
Elixir of Life
Alchemists not only wanted to convert metals to gold, but also wanted to finda chemical concoction that would enable people to live longer and cure all ailments. This elixir of life never happened either. -
430 BCE
Democritus of ancient Greece
Democritus proclaims the atom to be the simplest unit of matter. All matter was composed of atoms. -
300 BCE
Aristole of ancient Greece
Aristole delcares the existence of only four elements: fire, air, water, and earth. All matter is made up of these foyr elements. Matter had four properties: hot, cold, dry, and wet. -
Disproving of the Phlogiston Theory
Joseph Priestley heated calx of mercury, collected the colorless gas and burned different substances in this colorless gas. Called the gas "dephlogisticated air", but it was actually oxygen. -
Disproving of the Pholgiston Theory
Antoine Lavosisier was the one who disproved the Phlogiston Theory. He renamed the "dephlogisticated air" oxygen when he realized that the oxygen was part of air that combines with substances as they burn. Because of Lavoisier's work, he is now called the "Father of Modern Chemistry". -
Dalton's Atomic Theory
John Dalton publishes his Atomic Theory which states that all matter is composed of atoms, which are small and indivisible. -
William Crookes
He made headway in modern atomic theory when he used the vacuum tube made by Heinrich Geissler to discover cathode rays. He created a glass vacuum tube which had a zinc sulfide coating on the inside of one end, a metal cathode imbedded in the other end, and a metal anode in the shape of a cross in the middle of the tube. When electricity was run through the apparatus, an image of the cross appeared and the zinc sulfide glowed. -
Eugene Goldstein Discovery
Discovered positive particles by using a tube filled with hydrogen gas. the positive particle had a charge equal and opposite to the electron. Also has a mass of 1.66E-24 grams or one atomic mass unit. Positive particle was named proton. -
X-rays
Wihelm Roentgen accidentally discovered x-rays while researching the glow produced by cathode rays. Performed his research on cathode rays within a dark room, during his research, noticed that a bottle of barium platinocyanide was glowing on a shelf. Discovered the rays were causing the fluorescence. Could pass through glass, cardboard, and walls. Rays were called x-rays. -
Pitchblend
Henri Becquerel was studying the flourscence of pitchblend when he dicovered a prooerty of the pitchblend compound. Pitchblend gave a fluorescent light with or without the aid of sunlight. -
Rdioactive Elements
J.J Thomson placed Crookes tube with a magnetic field. He found that the cathode rays were negatively charged and each charge had a mass ratio of 1.759E8 columbs per gram. Concluded that all atoms have this negative charge and he renamed the cathode rays electrons. -
Mass of the Eletrons
Robert Milikan discovered the mass of sn electron by introducing charged oil droplets into an electrically charged field. Electron was found to be1.602E-19 columbs. Using Thomson mass ration, Milikan found the mass of one eletron to be 9.11E-28 grams. -
Protons within a Nucleus
Henry Moseley attemptsto use x-rays to determine the number of protons in the nucleus of each atom. Was unsuccessful because the neutron had not been discovered yet.
