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500 BCE
The Alchemist
A group of men who believed that any metal could be turned to gold. -
400 BCE
Demoritus
Democritus was a Greek philosopher who lived between 470-380 B.C. He developed the concept of the 'atom', Greek for 'indivisible'. Democritus believed that everything in the universe was made up of atoms, which were microscopic and indestructible. -
338 BCE
Aristotle
Aristotle founded the study of formal logic, systematizing logical arguments – he is famous for the syllogism, a method by which known information can be used to prove a point. In a syllogism two premises that are believed to be true – one major, another minor – are used to produce a conclusion. -
330 BCE
plato
Plato's cosmology derives from a mathematical discover by Empedocles. He found that there are only five solid shapes whose sides are made from regular polygons (triangles, squares, pentagons, hexagons, etc) -
330 BCE
solar system model
Plato first proposed that the planets followed perfect circular orbits around the Earth. Later, Heraclides (330 B.C.) developed the first Solar System model, placing the planets in order from the Earth it was is now called the geocentric solar system model. -
Robert Boyle
He was an Anglo-Irish natural philosopher, chemist, physicist and inventor. -
Lavoisier
Lavoisier is most noted for his discovery of the role oxygen plays in combustion. He recognized and named oxygen) and hydrogen (1783), and opposed the phlogiston theory. Lavoisier helped construct the metric system, wrote the first extensive list of elements, and helped to reform chemical nomenclature. -
John Dalton
Dalton's experiments on gases led to his discovery that the total pressure of a mixture of gases amounted to the sum of the partial pressures that each individual gas exerted while occupying the same space. -
solid sphere of billard ball model
Because Dalton thought atoms were the smallest particles of matter, he envisioned them as solid, hard spheres, like billiard (pool) balls, so he used wooden balls to model them. ... Dalton added these so the model atoms could be joined together with hooks and used to model compounds. -
Dmitri Mendeleev
Russian chemist Dmitri Mendeleev jotted down the symbols for the chemical elements, putting them in order according to their atomic weights and inventing the periodic table. -
Robert Millikan
During the 1890s the theory that electricity was conveyed by a miniscule unit, the electron, gained acceptance. In 1910 Robert Millikan succeeded in precisely determining the magnitude of the electron's charge. -
J.J. Thompson
J.J. Thomson discovered the electron by experimenting with a Crookes, or cathode ray, tube. He demonstrated that cathode rays were negatively charged. In addition, he also studied positively charged particles in neon gas. -
Plum pudding model
This led Thomson to propose that atoms could be described as negative particles floating within a soup of diffuse positive charge. This model is often called the plum pudding model of the atom, due to the fact that its description is very similar to plum pudding, a popular English dessert -
The curies
Marie Curie was a physicist, chemist and a pioneer in the study of radiation. She and her husband, Pierre, discovered the elements polonium and radium. -
Albert einstein
Albert Einstein laid much of the foundation for modern physics. Some other of his discoveries include: Photons - In 1905 Einstein came up with the concept that light is made up of particles called photons. Most scientists of his day didn't agree, but later experiments showed this to be the case. -
Ernest Rutherford
Ernest Rutherford postulated the nuclear structure of the atom, discovered alpha and beta rays, and proposed the laws of radioactive decay. He received the Nobel Prize in Chemistry in 1908. -
Neils Bohr
he was a Danish physicist who made foundational contributions to understanding atomic structure and quantum theory. -
Henry G.J. Mosely
while working at the University of Manchester, he observed and measured the X-ray spectra of various chemical elements using diffraction in crystals. 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
An electron cloud model is different from the older Bohr atomic model by Niels Bohr. Bohr talked about electrons orbiting the nucleus. The electron cloud model says that we cannot know exactly where an electron is at any given time, but the electrons are more likely to be in specific areas. -
Werner Heisenberg
Werner Heisenberg, in full Werner Karl Heisenberg, (born December 5, 1901, Würzburg, Germany—died February 1, 1976, Munich, West Germany), German physicist and philosopher who discovered a way to formulate quantum mechanics in terms of matrices. For that discovery, he was awarded the Nobel Prize for Physics for 1932.
