The Alchemists were able to break down the chemical compositions of what they thought were elements (wind, fire, water). This would eventually lead to the creation of the periodic table.
Proposed that matter could not be infinitely divided, and that atoms were the smallest piece of matter.
Originated the theory of atomism, which is the theory that everything is made of atoms.
Did not believe in atoms. He thought that there were only five elements (earth, air, water, fire, and aether) and that all matter was either made of one of these elements, or a combination of these elements.
The Roman Empire
64 A.D. - 1453 A.D
The Dark Ages
500 A.D. - 1500 A.D.
Figured out that syphilis is caused by inhaling metal vapors, and small amounts of mercury could treat it.
Developed the Phlogiston theory.
Proved Aristotle's theory wrong. He proposed the idea that there are more than 5 elements, and that these elements cannot be separated into simple components.
Carl Wilhelm Scheele
He discovered oxygen, but he wasn’t given credit for it.
Proposed the Law Of Conservation of Mass, and the Combustion Theory.
He was credited for discovering oxygen.
Published his law of definite proportions.
Proposed 4 basic ideas of atomic theory: all elements are made of atoms, atoms of the same element are alike, atoms of different elements are different, and compounds are made by forming two or more elements.
Joseph Gay Lussac
He discovered that at the same temperature and pressure, two volumes of hydrogen gas reacted with one volume of oxygen gas to produce two volumes of water.
Proposed the Avogadro Hypothesis, which states that gasses that are the same temperature, pressure, and volume have the same number of atoms.
Jöns Jacob Berzelius
Had obtained the atomic weights of at least 45 elements, and he was the one to start making symbols for each element (for example, the symbol for carbon monoxide is CO)
Sir William Crookes
Created the Crookes tube, which would eventually help J.J. Thomas and other scientists discover new information about the atom.
Discovered that atoms could be radioactive.
Created the “Plum Pudding” model, which is where positively charged substances surrounded the negatively charged electron. This is what he thought an atom was. He also discovered electrons.
The originator of the quantum theory of energy.
He proved the Plum Pudding Model wrong, and proposed that atoms had a positively charged nucleus and electrons were scattered between the nucleus and the atoms edge.
Proposed that electrons travel in specific orbits (energy levels) around the nucleus.
Discovered that the periodic table is best organized by atomic number.
His oil drop experiment helped quantify an electron’s charge, which resulted in a better understanding of atoms and their structure.
Discovered that no two electrons in an atom can exist in the same quantum state.
His theories of quantum mechanics and uncertainty led to the discovery of allotropic forms of hydrogen.
He developed the “Electron Cloud Model.” This model shows that a dense nucleus in the middle of an atom is surrounded by a cloud of electrons.
The first person to take notice of quantum tunneling. He also developed his Rule of Maximum Multiplicity.