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400 BCE
Democritus
Made the atomic theory that says everything is made up of atoms, there is empty space between atoms, atoms can't be destroyed, they're always in motion, and the number of atoms in infinite. -
360 BCE
Plato
Thought atoms break down into triangles, not spheres and made four element theory. He is known for the disciple of Socrates. -
500
The Alchemists
The Alchemists created experiments with Aristotle's idea of matter and did experiments to change metal into gold. They created the base for scientists to discover the atom. -
Robert Boyle
Discovered matter is made out of tiny particles in 1661, and that pressure and volume of a gas are related. He called the tiny particles corpuscles, that have become what we know as atoms. -
Antone Lavoiser
Created the law of conservation of mass that defined that matter was made of atoms. Discovered that atoms cannot be created or destroyed in chemical reactions. He also made the first periodic table, although it did not arrange by atomic mass. -
John Dalton
Proposed idea of atomic theory of matter, that all matter is made up of tiny particles called atoms, and masses and properties differ between elements. -
Billiard Ball Model
The Billiard Ball Model was made by John Dalton because he thought atoms were the smallest form of matter. -
Amedeo Avogadro
He proposed that equal volumes of gases at equal temperatures and pressure contain the same amount of particles. -
Dmitri Mendeleev
Dmitri Mendeleev made the first periodic table and discovered the periodic law which states that elements in order of increasing atomic mass have repeating properties. He was also given the davy medal in 1882. -
Pierre and Marie Curie
Pierre and Marie Curie tested all known elements, and discovered radium and polonium. Marie Curie died by radiation. -
J.J. Thomson
He made experiments with cathode ray tubes that showed all atoms have electrons. Because of this he is credited to be the first to discover electrons. In 1903 he proposed the plum pudding model. -
Plum Pudding Model
The Plum Pudding Model was made by JJ Thomson in 1904, and was a model of the atom to show the negatively charged electrons, but did not have a nucleus or protons with instead a positive charge surrounding the electrons. -
Albert Einstein
Proved that atoms exist and are always in random motion. Also made the equation of the atomic bomb. -
Robert Milikan
Proved the charge of electrons. -
Ernest Rutherford
Ernest Rutherford found that the atom is mostly empty with a positively nucleus surrounded by negativity charged electrons. He also discovered two types od radiation. -
Neils Bohr
Made the Bohr model that showed the structure of atoms. He also discovered Hydrogen. -
Solar System Model
The Solar System Model was made by Neils Bohr and showed the subatomic particles orbiting around the Nucleus like how planets orbit around the sun. -
Henry G. J. Moseley
He concluded that the atomic number is the number of positive charges in the atomic nucleus. He also fought in world war one. -
Electron Cloud Model
Made by Erwin Schrodinger in 1926, the Electron Cloud Model shows where electrons might be found with a nucleus in the center. The electrons don't orbit around the nucleus in this model. -
James Chadwick
James Chadwick identified the proton, and made the model of the hydrogen atom with Rutherford. He also realized protons and neutrons have equal mass. He received the nobel prize for physics in 1935.