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427 BCE
Plato
A theory that all solid forms of matter are composed of indivisible elements shaped like triangles. -
400 BCE
Democritus
He said that atoms are uniform, incompressible, and moved in infinite numbers. -
330 BCE
Solar System Model
This was made to teach about planets and the environments around them. The most accepted model is called the Nebular Hypothesis. -
1500
The Alchemists
They created a medieval idea that all metals were composed of sulfur and mercury in different proportions. -
Robert Boyle
He believed that everything is composed of very tiny particles. He also thought that everything was made out of atoms. -
Antone Lavoisier
He defined conservation of mass and contributed to discovery of atomic model. -
John Dalton
He suggested all matter is invisible and indestructible with mass and property. This combination was determined to be the physical nature of constituent elements. -
Billiard Ball Model
This idea was thought out by John Dalton and defines that atoms have a ball-like structure and couldn't be broken into smaller parts. -
Amedeo Avogadro
He formulated the Avogadro's Law. This stated that all gases at same temperature and pressure have the same amount of molecules per volume. He was an early figure in atomic theory. -
Dmitri Mendeleev
He created his version of the periodic table listing the most known elements at that time of their ascending atomic mass. He believed that atoms are entities where chemical elements are made out of. -
JJ Thompson
He discovered that all atoms contain electrons. He used the plum pudding as a model. -
Pierre and Marie Curie
They discovered the elements polonium and radium. They made the radioactivity for the random emission of ionizing, penetrating rays of certain atoms.. -
Plum Pudding Model
This model represents that electrons are imbedded in an even sphere of a posotive charge like the plum bits are in the pudding. -
Albert Einstein
He proved existence of atoms. He claimed that electrons could leave metal through light. -
Ernest Rutherford
He made the discovery that all atoms contain a positive charge nucleus smaller than the actual atom. -
Robert Millikan
He discovered charge of an individual electron. Conducted famous oil-drop experiment. -
Henry G. J. Mosely
He arranged the elements on the periodic table according to atomic numbers. He also found out the identity of an element is how many protons it has. -
Electron Cloud Model
This model represents the area of an atoms nucleus where you find electrons. -
Erwin Schrödinger
He created the electron cloud model representing the quantization of the hydrogen atoms energy levels. -
Werner Heisenberg
He introduced people to the uncertainty principal which stated that the position and momentum of an electron can never be correctly determined. -
James Chadwick
He discovered the neutron. He also found out that that a neutron has the same mass of a proton. -
Neils Bohr
He created atomic model of hydrogen atom based on quantum theory. He won a Nobel Peace prize for his findings.