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500 BCE
The Alchemists
The Alchemists proposed the idea that all metals ae made up of mercury and sulfur and that it is possible to change base metals into gold. -
430 BCE
Democritus
Democritus's model stated that matter consists of invisible particles called atoms and a void (empty space). He stated that atoms are indestructible and unchangeable. ... His atomic model was solid, and stated all atoms differ in size, shape, mass, position and arrangement, with a void exists between them -
427 BCE
Plato
Plato introduced the atomic theory in which ideal geometric forms serve as atoms, 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). -
322 BCE
Aristotle
Aristotle is a towering figure in ancient Greek philosophy, who made important contributions to logic, criticism, rhetoric, physics, biology, psychology, mathematics, metaphysics, ethics, and politics. -
1543
Solar System Model
Nicolaus Copernicus Came up with the idea that the sun is the center of the universe and based off his conclusion he came up with the Solar System Model. He said that the planets moved around the sun in a perfect circle so that's how he made the Solar System Model. -
Robert Boyle
Robert Boyle's major contribution to the atomic theory was that he helped develop a definition of an element ( any substance that can be broken into 2 or more substances is not an element) and helped with " the death" of the four elements -
Lavoisier
Lavoisier who through a series of experiments found that the total mass of products and reactants in a chemical reactions is always the same. This led to the theory of the law of conservation of mass. -
Billiard Bill Model
John Dalton Thought that Atoms were the smallest particles of matter. He envisioned them as small hard spheres thing he used pool balls to make his example of the model -
John Dalton
John Dalton was a schoolteacher, a meteorologist, and an expert on color blindness. However he was best know for his theory on atomism, he developed methods to calculate atomic weights and structures and formulated the law of partial pressures. -
Dmitri Mendeleev
Dmitri Mendeleev was an Russian chemist who developed the periodic classification of the elements. Mendeleev found that, when all the known chemical elements were arranged in order of increasing atomic weight, the resulting table displayed a recurring pattern, or periodicity, of properties within groups of elements -
The Curies
Curie conducted her own experiments on uranium rays and discovered that they remained constant, no matter the condition or form of the uranium. The rays, she theorized, came from the element's atomic structure. -
Plum pudding model
The Plum pudding model showed how an atom that had a positively charged medium, or space, with negatively charged electrons inside the medium. -
J.J. Thomson
J.J. Thomson the inventor of the plum pudding model used cathode ray tubes to prove that that all atoms contain tiny negatively charged subatomic particles or electrons within them. Then with this information Thomson proposed the plum pudding model of the atom, which had negatively-charged electrons embedded within a positively-charged "soup." -
Albert Einstein
Einstein mathematically proved the existence of atoms, and thus helped revolutionize all the sciences through the use of statistics and probability. Atomic theory says that any liquid is made up of molecules -
Robert Millikan
Robert Millikan did an oil drop experiment which helped to quantify the charge of an electron, which contributed greatly to our understanding of the structure of the atom and atomic theory. -
Ernest Rutherford
Ernest Rutherford found that the atom is mostly empty space, with nearly all of its mass concentrated in a tiny central nucleus. The nucleus is positively charged and surrounded at a great distance by the negatively charged electrons -
Neils bohr
Neil Bohr made up the Bohr model which showed how electrons travel in defined circular orbits around the nucleus. The orbits are labeled by an integer, the quantum number n. Electrons can jump from one orbit to another by emitting or absorbing energy. -
Henry G.J. Mosely
Through this, he discovered a systematic relation between wave- length and atomic number. This discovery is now known as Moseley's Law. -
Electron cloud model
The Electron model was made in 1925 by Werner Heisenberg And Erwin Schrödinger. Erwin proposed that electrons travel in waves, which means their exact positions cannot be determined. He developed an equation to calculate the chances of an electron being in any given place. So from is conclusion he made the Electron cloud model. -
Werner Heisenberg
Werner Heisenberg 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.
