-
500 BCE
The Alchemists
Using Aristotle's ideas they began to treat metal to change them into a different material. They created experiments that led to the atoms discovery -
460 BCE
Democritus
He came up with the theory that everything was made up of smaller bits, he also came up the idea that different shaped atoms caused different properties -
427 BCE
Plato
He used the concept of the atomic theory in which geometric forms are atoms, and that they can be broken down into triangles. -
Robert Boyle
He discovered that atoms exist based on the relation between pressure and volume on gas. His law states that as pressure increases volume decreases -
Antoine Lavoisier
He was the first person known to make use of the balance, he was known for separating particles. He came up with the law of conservation -
John Dalton
John Dalton cam up the the theory that everything is made of atoms, that atoms can't be destroyed, and that all atoms of an element are identical -
Billiard Ball Model
This model was Dalton's guess on what the atom looked like, which he guessed was a solid sphere. Because of this he chose to model a billiards ball. -
Amedeo Avogadro
He discovered that elements could be made of more than one atom, for example; oxygen -
Plum Pudding Model
The Plum Pudding model was proposed by JJ Thompson after the electron was discovered, this model explained the known parts of the atom -
JJ Thompson
JJ Thompson discovered the electron, and came up with the Thompson atomic theory that many future scientists used for experiments -
Pierre and Marie Curie
The Curies discovered and isolated radium, an element that disintegrated into other elements this discovery began to disprove the assumption that the atom was indivisible -
Albert Einstein
He proved that atoms truly existed and he also demonstrated electrons could leave metal with the use of light -
Ernest Rutherford
Ernest Rutherford created a model that described atoms as small, dense, particles with a positively charged nucleus which electrons orbit -
Robert Millikan
Discovered the fundamental charge of an atom, the electron, and that the electron has a negative charge -
Neils Bohr
Created a model of the atom where the electrons only occupied certain nucleus orbits, he was also the first to use quantum theory -
Henry J. Mosely
Henry J. Mosely's experiments showed the major properties of an element were found by the atomic number not the weight -
Solar System Model
A model that showed an atom compared to the solar system and its similarities. The sun being the nucleus and the electrons being planets in orbit -
James Chadwich
Chadwich discovered the neutron, a particle with neither positive or negative charge, they had no electric charge at all. He also discovered that the neutron made up part of an atoms nucleus -
Werner Heisenberg
Heisenberg discovered the uncertainty principle, that a particles position and momentum can't be known -
Erwin Schrödinger
Schrodinger found that electrons behavior could be explained by mathematically treating them as waves -
Electron Cloud Model
Discovered by Erwin Schrodinger, this model showed the general area that a moving electron is most likely to be