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Period: 460 BCE to 370 BCE
Democritus
First known definition of an atom
“The smallest unit of matter which still retains the identity and properties of that matter.” -
Period: 384 BCE to 322 BCE
Aristotle
He refuted Democritus and believed in 4 elements, Earth, air, fire, and water. He lead to 2000 years of false sciences. -
360 BCE
Elements
Plato coins the term Elements in a dialogue about the composition of organic and inorganic bodies -
332 BCE
Greeks
Alexander the Great takes over Egypt and their interest in science increases, and specifically their belief in Aristotle’s 4 elements. -
Period: 600 to 700
Arabs
Arabs occupy Egypt and further their understanding of science. They spread their understanding into Spain.
Gold was seen as the perfect metal. Alchemist sought to find spiritual purification and immortality. -
1250
Better distillation
Tadeo develops fractional distillation, which was better than its predecessors. -
1500
Separation
The west focused on our modern understanding of chemistry, finding new compounds and substances. They also Invented Distillation, percolation, extraction, rudimentary
chromatography.
The other created our modern understanding of Alchemy, focused on the spiritual and metaphysical side. -
1500
16th century
They believed living things were fundamentally different from non-living things. Living things contain a “vital spirit” -
First textbooks
Andreas Libavius publishes a prototype chemistry textbook. -
Jean Beguin
Created an early chemistry book that included the first ever chemical equation. -
Boyle’s Law
Robert Boyle proposes a law, which was an experimentally based description on the behavior of gasses, and how it related to the volume and the pressure. -
Phlogiston
They believed if a combustible object caught fire it would release the phlogiston that was contained within it. First proposed by Johann Becker -
Period: to
Modern Chemistry
Anton Laurent de La Voisier Is seen as the father of modern chemistry because he relied on quantitative observations to make conclusions. He disproved the theory of phlogiston by proving that oxygen caused combustion. He found out that matter cannot be created or destroyed during a chemical reaction. -
Benjamin Franklin
He discover that electrical charges comes in 2 variations, one that has a negative charge, and one that has a positive charge. -
Law of Definite Proportions
Joseph Proust came up with the theory that a chemical compound always contains exactly the same proportion of elements by mass -
Period: to
John Dalton
Father of Atomic theory. Dalton believed matter was made up of atoms that could not be seen or destroyed. He thought all atoms of an element were identical. This was later found to be untrue. He thought elements of different compounds have different weights and chemical properties and can be combined to form compounds. He also discovered that atoms cannot be created of destroyed, and when a compound decomposes, the atoms from it are recovered. -
Period: to
William Crookes
Discovered that the cathode ray has mass since paddle wheel spun when put in a crt and turned on the battery. -
Periodic Table?
Lothar Meyer creates an early version of what is now known as the periodic table with only 28 elements, which were organized by valance. -
Indigo dye
Adolf Baeyer began work on indigo dye, which would revolutionize the dye industry. -
John Thomson
Thomson continued to experiment on the crt, he discovered that ray deflected away from negative charges and towards positive ones. He deduced that the ray was made of negative particles, which he named electrons. -
Period: to
Ernest Rutherford
He came up with the classification for radiation.
He created an experiment where he put a sheet of gold foil in a tin can and aimed a ray of alpha radiation at the foil.
Most of the time the ray lit up the can right behind the foil. This told him that he had hit something massive and dense at the center of the atom. He deducted that atoms are mostly empty spaces, there must be a core at the center of the atom, and the core must be positively charged. -
Bequerel
Discovered radioactivity coming from uranium ore. -
Marie and Pierre
They discovered isolated polonium and radium inside of uranium ore. The research into radioactivity gave birth to an idea that there was something that gave the atoms its identity and that if you changed that, you could change the atom. -
pH
S. P. L. Sørensen invents the concept of the pH scale and developed was to find the acidity of substances. -
Millikan
He calculated the mass and charge of electrons. -
Harbor-Bosch
German chemist Fritz Harbor and Carol Bosch found a way to combine atmospheric Nitrogen with hydrogen to create ammonium. This is still used today for crop fertilization -
Period: to
Penicillin
During these 10ish years, research on a bacteria that was originally found by Alexander Fleming, however he wasn’t able to find a way to extract a usable quantity of penicillin from it. In 1939 Howard Florey and his team figured out a way of purifying it. Full scale production of this would start in 1944 -
James Chadwick
He proved there was another subatomic particle, with no charge, called a neutron.