-
400 BCE
Democritus
Democritus discovers the atomos. “That which cannot be cut.” -
322
Alexander
Alexander the Great conquered Egypt. The Greek philosophers were interested in the Egyptian religion. So the cultures philosophies merged and alchemy was created. -
Period: 384 to 322
Aristotle
Aristotle refuted Democritus and his discovery of the atom. Aristotle was a firm believer in the elements. However this led to bogus science for about 2000 years. -
600
Further science
Arabs occupied Egypt and further developed the science. -
700
Spreading
The Arabs spread it to Spain in the 700s -
Period: 700 to
Alchemists, spiritual purity, and immortality
Metals are made up of mercury and sulfur in varying proportions.
Gold is the perfect metal and all others were “Baser” metals, capable of being transmuted into gold by means of a substance known as the Philosophers Stone. Alchemists applied this concept of purification and search for perfection to the human condition, and sought spiritual purification and immortality -
The phlogiston theory
From Ancient Greek phlogistón “burning up”
First stated in 1667 by Johann Becher -
Period: to
Father of Modern Chemistry
Anton Laurent de La Voisier, he was called he relied on quantitative observation to develop conclusions. Dispelled the Phlogiston Theory by proving that oxygen causes combustion, he also discovered the Law of the conservation of mass. -
Benjamin Franklin
Discovered that electrical charges come in 2 varieties – positive and negative. Like charges repel, opposite charges attract. -
Joseph Louis Proust
He found the Law of Constant Composition -
Period: to
John Dalton
Known as the father of atomic theory. He said that matter is just atoms that are invisible and indestructible and that all atoms of an element are identical. He also said atoms of different elements have different weights and different chemical properties, and that these atoms combine in simple whole numbers to create compounds. He said that atoms cannot be created or destroyed. When a compound decomposes, the atoms are recovered unchanged -
Cathode ray tube
CRT – a glass tube that doesn’t have air or matter inside, coated with fluorescent paint. When connected to a battery, the paint glows, indicating that there is some type of radiation present in the battery -
John Joseph Thomson
Continued experimenting on the CRT and deduced that the cathode Ray was made of negative particles that he named electrons -
Ernest Rutherford
He classified radiation into Alpha, Beta, and Gamma rays. He also classified their speed, behavior, and charge. -
Becquerel
Discovered that uranium was radioactive -
Marie and Pierre Curie
Found and trapped polonium and radium from uranium ore -
Millikan
Calculated the mass and charge of an electron -
Gold foil experiment
He stretched a sheet of gold foil in a tin can and coated the inside of the can with fluorescent paint, he aimed a ray of alpha radiation at it and expected the ray to go through the metal and light up the fluorescent paint. 99.9% of the time it worked, .1% of the time it did the opposite. He deduced that the ray had hit something massive and dense. He said that atoms are mostly empty space but must have a solid core. -
James Chadwick
Proved the existence of a subatomic particle that had no charge, he called it the neutron