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500 BCE
The Alchemists
Develop theory that all metals are composed of mercury and sulfur and that it is possible to change base metals into gold. -
442 BCE
Democritus
Greek philosopher, who develop the atomy theory of the universe, his atomy theory anticipated the modern principles of the conservation of energy and the irreducibility of matter. -
427 BCE
Plato
According to which atoms broke down mathematically into triangles, such that the form elements had the following shape .fire (tetrahedron), air (octahedron), water (icosahedron), earth (cube). -
332 BCE
Aristotle
Aristotle was born in Stagira, in 384 B.C. and died in 322 B.C. Also, because there was still little technology, Aristotle was unable to perform complex experiments. However, Aristotle created a form of logic. Aristotle used his observation to determine his conclusions on atomic theory. This theory lasted for quite some time because the other scientists did not come around until a while later. This theory may seem more general, and it is, which is most likely why it lasted so long. -
Robert Boyle
Is know as ''The father of chemistry '' for his discovery that atoms must must exist based on the relationship between pressure and volume of gas . -
Lavoisier
26 August 1743 – 8 May 1794 was a French nobleman and chemist who was central to the 18th-century chemical revolution and who had a large influence on both the history of chemistry and the history of biology. Lavoisier is most noted for his discovery of the role oxygen plays in combustion. He recognized and named oxygen (1778) and hydrogen (1783). -
John Dalton
Was an English chemist, physicist, and meteorologist. He is best known for proposing the modern atomic theory. "Elements consisted of atoms that were identical and had the same mass and that compounds were atoms from different elements combined together." -
Dmitri Mendeleev
was a Russian chemist and inventor. He is best remembered for formulating the Periodic Law and creating a farsighted version of the periodic table of elements. He used the Periodic Law not only to correct the then-accepted properties of some known elements, such as the valence and atomic weight of uranium, but also to predict the properties of eight elements that were yet to be discovered. -
J.J. Thomson
18 December 1856 – 30 August 1940 was a British physicist and Nobel Laureate in Physics, credited with the discovery of the electron, the first subatomic particle to be discovered. discovery of the electron, but before the discovery of the atomic nucleus, the model tried to explain two properties of atoms then known: that electrons are negatively-charged particles and that atoms have no net electric charge. -
The Curies
Pierre Curie and his wife Marie Curie started that radioactive materials cause atoms to break down spontaneously, realizing radiation in the form of energy particles. -
albert einstein
born in Ulm, Germany, and lived from 1879-1955.,Einstein's biggest contribution to the Atomic Theory was that he was able to fully prove through usage of evidence that atoms did indeed exist, and he was also able to demonstrate that electrons could leave metal through usage of light. He also created the mass energy equivalence equation, and this paved the way for the creation of the atomic bomb. -
Robert Millikan
was an American experimental physicist . Millikan to his first important discovery of the elementary charge of electricity through use of his elegant "falling drop method", measuring the constant charge and quanta of electrons, the direct determination of Planck's Constant, confirmation of the atomic theory of matter, and experiments in spectroscopy beyond ultraviolet radiation levels. -
Ernest Rutherford
The model described the atom as a tiny, dense, positively charged core called a nucleus, in which nearly all the mass is concentrated, around which the light, negative constituents, called electrons, circulate at some distance, much like planets revolving around the Sun. -
Neils Bohr
Made numerous contributions one of them was. Atoms are mostly empty space with a positively charged nucleus surrounded by electrons that travel in circular orbits (like the solar system.) -
Henry G.J. Mosely
(23 November 1887 – 10 August 1915) was an English physicist, whose contribution to the science of physics was the justification from physical laws of the previous empirical and chemical concept of the atomic number. This stemmed from his development of Moseley's law in X-ray spectra. -
Werner Heisenberg
5 December 1901 – 1 February 1976) was a German theoretical physicist and one of the key pioneers of quantum mechanics contributed to atomic theory through formulating quantum mechanics in terms of matrices and in discovering the uncertainty principle, which states that a particle’s position and momentum cannot both be known exactly.
