-
460 BCE
Democritus
One of the first atomic theorists was Democritus, a Greek philosopher who lived in the fifth century BC. Democritus knew that if a stone was divided in half, the two halves would have essentially the same properties as the whole. -
300 BCE
Aristotle
Aristotle disagreed with Democritus' theory. He was also a philosopher, not a scientist. He believed you could understand and figure out things by simply thinking about them. He also believed that everything was a combination of the four elements: earth, fire, water, air. His theory was that a mass of incomprehensible size was everywhere; he called this 'hyle'. There was no separate 'particles' for each material, it was all one. -
1494
George Bauer
Gifted with a precocious intellect, Agricola early threw himself into the pursuit of the "new learning", with such effect that at the age of 24, he was appointed Rector extraordinarius of Greek at the so-called Great School of Zwickau, and made his appearance as a writer on philology. -
Robert Boyle
Robert Boyle wrote a book, In this book he overturned Aristotle’s conception of the four elements (the belief that everything was composed of earth, air, fire and water) and replaced it with the modern idea of an element—namely that an element is a substance that cannot be separated into simpler components by chemical methods. -
Antoine Lavoisier
The first breakthrough in the study of chemical reactions resulted from the work of the French chemist Antoine Lavoisier between 1772 and 1794. Lavoisier found that mass is conserved in a chemical reaction. ... But the number of hydrogen and oxygen atoms before and after the reaction is the same. -
Joseph Proust
Joseph Proust (1754 - 1826) He first published his Law of Definite Proportions (or Law of Constant Composition) in 1794. This law states that a compound is composed of exact proportions of elements by mass regardless of how the compound was created. -
John Dalton
Democritus first suggested the existence of the atom but it took almost two millennia before the atom was placed on a solid foothold as a fundamental chemical object by John Dalton (1766-1844). Although two centuries old, Dalton's atomic theory remains valid in modern chemical thought. 1) All matter is made of atoms. -
Amadeo Avogadro
Amedeo Avogadro is best known for his hypothesis that equal volumes of different gases contain an equal number of molecules, provided they are at the same temperature and pressure. His hypothesis was rejected by other scientists. It only gained acceptance after his death. It is now called Avogadro's law. -
Joseph Gay Lussac
French chemist Joseph Louis Gay-Lussac proposed two fundamental laws of gases in the early 19th century. While one is generally attributed to a fellow countryman, the other is well known as Gay-Lussac’s law. His daring ascents in hydrogen-filled balloons were key to his investigations. -
Henri Bccquerel
Henri Becquerel, in full Antoine-Henri Becquerel, (born December 15, 1852, Paris, France—died August 25, 1908, Le Croisic), French physicist who discovered radioactivity through his investigations of uranium and other substances. In 1903 he shared the Nobel Prize for Physics with Pierre and Marie Curie. -
J.J Thomson
Image result for jj thomson atomic theorywww.iun.edu
In 1897, J.J. Thomson discovered the electron by experimenting with a Crookes, or cathode ray, tube. He demonstrated that cathode rays were negatively charged. ... Thomson realized that the accepted model of an atom did not account for negatively or positively charged particles. -
Max Planck
(1858-1947) Max Planck, a German physicist, is best known as the originator of the quantum theory of energy for which he was awarded the Nobel Prize in 1918. His work contributed significantly to the understanding of atomic and subatomic processes. Planck was born in Kiel, Germany in 1858. -
Robert Millikan
Learn about the life and achievements of American physicist Robert Millikan. His oil drop experiment 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
Search Results
Featured snippet from the web
Image result for ernest rutherford atomic theory
Rutherford overturned Thomson's model in 1911 with his well-known gold foil experiment in which he demonstrated that the atom has a tiny and heavy nucleus. Rutherford designed an experiment to use the alpha particles emitted by a radioactive element as probes to the unseen world of atomic structure. -
Niels Bohr
Image result for niels bohr atomic theorythehistoryoftheatom.weebly.com
In 1913, Niels Bohr proposed a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities. Electrons should move around the nucleus but only in prescribed orbits. When jumping from one orbit to another with lower energy, a light quantum is emitted -
Erwin Schrodinger
In 1926 Erwin Schrödinger, an Austrian physicist, took the Bohr atom model one step further. Schrödinger used mathematical equations to describe the likelihood of finding an electron in a certain position. This atomic model is known as the quantum mechanical model of the atom. -
Louis De Broglie
Louis de Broglie (In full:Louis-Victor-Pierre-Raymond, 7th duc de Broglie) was an eminent French physicist. He gained worldwide acclaim for his groundbreaking work on quantum theory. In his 1924 thesis, he discovered the wave nature of electrons and suggested that all matter have wave properties. -
Contribution of physicists
He was a Denmark Physicist who made contributions to understanding the atomic structure and his creation of the quantum Theory. Contribution; 1913, Bohr developed the Bohr model (shows the atom as small with a positively charged nucleus surrounded by an electron). -
Werner Heisenberg
Heisenberg is best known for his uncertainty principle and theory of quantum mechanics, which he published at the age of twenty-three in 1925. He was awarded the Nobel Prize for Physics in 1932 for his subsequent research and application of this principle
