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Period: 460 BCE to 370 BCE
Democritus
Atoms cannot be cut. Atoms are the smallest unit of matter which still retains the identifies and properties of that matter. -
Period: 384 BCE to 322 BCE
Aristotle
Refuted Democritus. Believed in 4 elements: Earth, Air, Fire, and Water. Aristotle refuted Democritus Theory which led to nearly 2000 years of wrong science. -
300 BCE
Alchemy
Alchemy said that Metals are made up of mercury and sulfur in varying proportions. It also said gold is the perfect metal and all others were “Baser” metals, capable of being transmuted into gold. Also, Alchemists applied this idea of purification and search for perfection to the human condition, and sought spiritual purification and immortality. They invented Distillation, percolation, extraction, rudimentary chromatography. -
Period: to
Vitalism
Vitalsim decided that living organisms were fundamentally different from non living entities because they contain a vital spirit. Also, said that livings things were governed by different properties then inanimate things. -
Period: to
The Phlogiston Theroy
Discovered the existence of a fire like element called Phlogiston which was contained with combustible bodies and released during combustion. Declared that a substance that burned did so because it contained Phlogiston. -
Period: to
Anton La Voisier
Considered as the father of chemistry because he relied on quantitative observations to develope conclusions. He dispelled The Phlogiston Theory by proving that oxygen causes combustion. He also discovered the Law of Conservation of Mass: by proving that the mass of a metal oxide = the mass of metal plus oxygen when the metal oxide decomposes. Matter can change forms, but cannot be created nor destroyed in a chemical reaction. -
Benjamin Franklin
He discovered that electrical charge still come in 2 varieties: positive and negative. Charges alike repel and charges opposite attract. -
Joseph Louis Proust
The law of definite proportions also known as the law of constant composition. This law states that a chemical compound always contains exactly the same proportion of elements by mass. -
Period: to
John Dalton: Father of Atomic Theroy
His Theroy consist of matter being made up of atoms which are invisible and indestructible, all atoms of an element are identical, atoms of different elements combine in simple whole numbers to form compounds, atoms of different elements have different weights and different chemical properties, and atoms cannot be destroy nor made when a compound decomposes atoms are found unchanged. -
Period: to
William Crooke et. al.
Cathode Ray Tube (CRT): A glass tube that is evacuated coated with fluorescent paint. When connected to a battery the paint glows, indicating that there is some type of radiation streaming from the battery.
Patel Wheel Placed in CRT: When crookes placed a paddle wheel in the CRT and turned on the battery the wheel spun since the tube was evacuated this told Crookes that the Cathode Ray has mass. -
Sir John Joseph Thomson
He continued an expirement on the CRT. He used changed plates to deflect the cathode Ray. He found that the rap deflected away from the negative plate, and toward the positive. He also deduced that the cathode Ray was made of negative partials. He named them electron. -
Period: to
Ernest Rutherford
He made the Classification of radiation. He started the Famous Gold Foil Experiment. He also stretched a sheet of gold foil in a tin can and coated the inside of the can with fluorescent paint.
Aimed a ray of alpha radiation (+ charges) at the foil.
Expected that the alpha rays would pass right through the metal atoms in the foil, and the fluorescent coating would light up right behind the foil. -
Curies (Marie and Pierre)
He discovered and isolated polonium and radium from uranium ore. -
Becquerel
He discovered radioactivity in Uranium ore. -
Millikan
He calculated the mass and charges of electrons. -
James Chadwick
Proved the existence of another subatomic particle, that had no charge, named it the neutron.