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760 BCE
The Alchemists
They created experiments with the idea of matter. They believed that all metals were formed from mercury and sulfur. -
460 BCE
Democritus
He thought that atoms were tiny, empty space that muted at random. He introduced the idea of atoms as building blocks of matter. -
427 BCE
Plato
He theorized that solid forms of matter are composed of elements shaped like triangles. -
1162
Robert Boyle
He showed that matter is made of tiny particles he named corpuscles known now as atoms. -
Antone Lavoisier
He helped define laws of conservation mass which helped to shape the atmoic theory. He defined that matter was made of atoms that weren't created or destroyed during chemical reactions. -
John Dalton
His theory stated that all matter is made of atoms that are invisible. He claimed that all elements had its own type of atom. -
Amedeo Avogadro
He created multiple models. These included the electron cloud model, billiard ball model, solar system model, and plum pudding model. -
Pierre and Marie Currie
He hypothesized that radioactive particles cause atoms to break down and release radiation. -
JJ Thompson
He proposed that all matter is made up of tiny particles that are much smaller than atoms. -
Albert Einstein
He mathematically proved existence of atoms. Einstein realized that molecules would make statistical functions. -
Robert Millikan
He successfully determined the magnitude of an electrons charge. He proved this by doing multiple experiments with oil and metal plates. -
Ernest Rutherford
He discovered the atom is mostly empty space surrounding a massive nucleus. He predicted the existence of the neutron. -
Henry G.J. Mosely
He experimentally demonstrated that major properties of an element are determined by the atomic number, not by the atomic weight. -
Neils Bohr
He proposed a theory for hydrogen atoms. He said that electrons move around the nucleus but only in prescribed orbits. -
James Chadwich
Discovered that all matter is composed of different particles known as atoms. He also discovered the neutron. -
Dmitri Mendeleev
He devised the periodic table of elements. He found that, when all the chemical elements were arranged in order of increasing atomic weight.