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430 BCE
Plato
Plato created the theory of solid forms being made up of elements. Plato also said that elements rate indestructible and have a triangular shape. -
400 BCE
Democritus
Democritus stated that all matter was made up of particles. Not only this but he also created the idea of atoms existing. -
800
The Alchemists
The Alchemists discovered that sulfur and mercury make all metals with different ratios. They also manipulated matter properties creating valuable substances -
1473
Solar System Model
This was a way to represent the atom. The solar system parts are an element of the atom, the nucleus is the sun and the electrons are the planets. -
Robert Doyle
Researched all matter composed of tiny particles originally discovered by Democritus. Robert created the Boyle Law which states that the pressure of gas is related to the volume. -
Antone Lavoisier
Lavoisier helped shape the atomic theory with the Law of Conservation of Mass. The law states the mass is not destroyed by chemical reactions. -
Billiard Ball Model
The model showed the behavior of atoms and how atom combine with other atoms in a whole number ratio. This is also showed the formation of compounds. -
Amedeo Avogadro
Avogadro made a series of molecular experiments. Eventually he discovered that if two objects have the same amount of gas then the two objects have the same amount of molecules. -
John Dalton
Dalton created the Atomic Theory. The Atomic theory means that all matter is composed of atoms. He also discovered that atoms have masses and properties that differ. -
Dmitri Mendeleev
Mendeleev created the ‘principles of chemistry’. Dmitri also found an effective way to organize the elements. -
JJ Thomson
Thomson found out that electrons existed. JJ then proceeded to create a model of the atom. -
Pierre and Marie Currie
The Curies discovered the radioactivity of some of the elements. They proved the radioactivity of polonium and radium. -
Plum Pudding Model
The model showed the atoms balance. Meaning the negative charges counteract the positive charges inside an atom. -
Albert Einstein
Einstein mathematically proved that atoms were real. His proving helped the development of the atomic theory -
Robert Millikan
Millikan showed the the amount of electrical charge electrons hold. Robert found this out with his oil drop experiment. -
Ernest Rutherford
Rutherford made it clear that the mass of an atom is made up of the nucleus. The nucleus is made up of protons and neutrons. -
Neils Bohr
Neils Bohr took inspiration from Rutherfords model describing the atom. Bohr said the the electrons rotate around the nucleus containing different amounts of energy. -
Henry G J Mosley
Mosley proved that the atomic number is based off of the number of positive charges, also known as neutrons. Henry also published a document of this discovery. -
Electron Cloud Model
The model helped to create the atom model. The model showed the behavior of electrons and the area of the electrons. -
Erwin Schrödinger
Schrödinger made the modern version of the atom model. Erwin also showed the spread of electrons with math. -
Werner Heisenberg
Werner studied quantum mechanics and created the uncertainty relation. The uncertainty relation set boundries and determined how to find the position and velocity of a particle. -
James Chadwich
Proved the neutron’s existence within the atom. Chadwich also showed that the neutrons have no electrical charges.