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450 BCE
The Alchemists
The alchemists contributed to the atom by introducing that they thought matter could be eternal, and no matter could come from nothing. They thought material things are made from particles that are very small, and particles are always moving. -
440 BCE
Plato
He thought atoms themselves are indivisible, and atoms join together to create things. -
430 BCE
Democritus
He thought atoms were uniform, solid, hard, incompressible, and indestructible. He thought they moved in infinite numbers through infinite space until stopped. -
330 BCE
Solar System Model
This model introduced that the sun is the center of the universe and the planets move around it. Ernest Rutherford said that an atom is like this, with the nucleus in the center and the electrons around it. -
Robert Boyle
He demonstrated matter is made up of tiny particles. He also discovered the relationship between pressure and volume in a gas. -
Antone Lavoisier
He said an element is a substance that cant be decomposed into another one. -
John Dalton
He thought that matter is made up of atoms that are indivisible. He thought all atoms of the same element are identical and different atoms cant be created or destroyed. -
Billiard Ball Model
This model defined the atom to be a ball like structure. -
Amedeo Avogadro
He said volume of gas at the same amount and temperature contain the same amount of molecules. -
Dmitri Mendeleev
He built a systemic table of all 70 elements known. -
JJ Thomas
He discovered all atoms contain tiny negatively charged subatomic particles or electrons. -
Pierre & Marie Curie
They discovered radioactivity between elements, and they discovered radium. -
Plum Pudding Model
JJ Thompson made a model where all the electrons were embedded in a uniform sphere of positive charge. -
Albert Einstein
He mathematically predicted the size of both atoms and molecules. He did this by the movement of molecules in a liquid caused by the Brownian motion. -
Ernest Rutherford
He described the atoms as having a tiny dense and positive charged nucleus. He said the electrons revolve around the nucleus like planets around the sun. -
Neils Bohr
He made an atomic structure model, but they failed to explain the Zeeman effects and the Stark effect. -
Henry G J Mosely
He discovered each elements x-rays at a unique frequency. -
Robert Millikan
He discovered electrons are tiny negatively charged subatomic particles in all atoms. -
Electron Cloud Model
With this model, scientists could now make educated guesses with the position of the electrons. -
James Chadwich
He discovered the neutron and he measured the neutrons mass.