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469 BCE
The Atomos
Democritus formulated the theory of the atoms: the smallest unit of matter which still retains the identity and properties of that matter.
(Photo source: https://glamuur.ee/wp-content/uploads/2019/05/ERS-17.png) -
384 BCE
Earth, air, fire, and water
Aristotle refuted Democritus, postulated the theory of the four elements: Earth, Air, Fire, and Water; this caused 200 of years of pseudoscience.
(Photo resource: https://www.vectorstock.com/royalty-free-vectors/fire-wind-water-vectors) -
300
Alchemy
The medieval forerunner to chemistry, alchemy was based on the conversion metals into other substances. The word alchemy comes from the word Khemia, a Greek word meaning Egypt. As the Greek concept of the four elements was merged with Egyptian religion.
(Photo resource: https://www.factinate.com/things/42-dark-facts-medieval-alchemy/) -
Vitalism
A 16th century concept that sought to explain the animating principle behind life that distinguished it from non living matter. -
The Phlogiston Theory
A theory that describes a combustible element released during combustion.
(Photo resource: http://treetownchem.blogspot.com/2016/02/oxygens-alchemical-origins-phlogiston.html) -
Father of Modern Chemistry
Antoine Lavoisier considered the father of modern chemistry and beheaded during the French Revolution. Lavoisier proved oxygen was responsible for combustion, discovered the law of conservation of mass, and taught that matter could change form but could not be created nor destroyed.
(Photo resource: https://en.m.wikiquote.org/wiki/Antoine_Lavoisier) -
Benjamin Franklin
Franklin discovered positive and negative charges in electricity.
(Photo resource: https://en.m.wikipedia.org/wiki/Electric_charge) -
Joseph Louis Proust
He created The Law of Constant Composition, which states that a chemical compound always contains exactly the same proportion of elements by mass. He also discovered H2O always contains 88.9% O, 11.1% H by mass (Photo resource: http://scihi.org/joseph-proust-and-the-law-of-constant-composition/) -
The Father of Modern Atomic Theory
John Dalton formed the basis to modern atomic theory; Matter is made up of atoms that are indivisible and indestructible, all atoms of an element are identical, atoms of different elements have different weights and different chemical properties, atoms of different elements combine in simple whole numbers to form compounds, atoms cannot be created or destroyed, and when a compound decomposes, the atoms are recovered unchanged. -
William Crookes and his Tube
A Crookes tube is an early experimental tube invented by William Crookes
(Photo resource: https://nationalmaglab.org/education/magnet-academy/history-of-electricity-magnetism/pioneers/william-crookes) -
Sir John Joseph Thomson
Thompson continued experimenting on the cathode tube and discovered negatively charged particles he called electrons
(Photo resources: https://www.livescience.com/45590-electrons-have-split-personalities.html) -
Becquerel
Becquerel radioactivity in a uranium ore
(Photo resource: https://www.heart.org/en/news/2019/05/03/regular-low-level-radiation-exposure-raises-high-blood-pressure-risk) -
Madame Curie
Marie and Pierre Curie discovered and isolated polonium and radium from uranium ores
Which would later lead to radiation poisoning
(Photo resource: https://www.nobelprize.org/prizes/physics/1903/marie-curie/biographical/) -
Millikan
Millikan calculated the mass and charge of an electron
(Photo resource: https://m.youtube.com/watch?v=UTdQCZTxkbY) -
Ernest Rutherford
Rutherford deduced from his experiments that atoms have a core that was positively charged but were mostly made of empty space
(Photo resources: https://en.m.wikipedia.org/wiki/Ernest_Rutherford) -
James Chadwick
He discovered the neutron, a particle with no charge.
(Photo resource: http://business.parkrapids.com/news/details/jimmy-neutron-star-of-nickelodeon-s-popular-animated-series-meet-area-kids-in-park-rapids)
