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Aristotle
Aristotle thought that all materials on Earth were not made of atoms, but of the four elements, Earth, Fire, Water, and Air. He believed all substances were made of small amounts of these four elements of matter.
https://the-history-of-the-atom.wikispaces.com/Aristotle -
400
Bohr
Father of the atom; believed that all things consisted of tiny individual units called atoms.
Notebook -
Johann Becher
Developed the Phlogiston theory; when something burned, it lost phlogiston to the air http://cstl-csm.semo.edu/cwmcgowan/ch181/atomhist.htm -
Robert Boyle
Discussed the probability of atoms existing. He proposed that elements are composed of 'corpuscles' of various types and sizes that are able to organize themselves into groups that represent different chemical substances. http://historyoftheatomictheory.weebly.com/robert-boyle.html -
Isaac Newton
Newton proposed a mechanical universe where small solid masses were in motion. In short, he believed that there were little tiny pieces of mass that were 'swimming' everywhere.
https://www.timetoast.com/timelines/962152 -
Joseph Priestly
He discovered oxygen, which he called dephlogisticated air.
http://cstl-csm.semo.edu/cwmcgowan/ch181/atomhist.htm -
Antoine Lavoisier
He proposed the Combustion Theory which was based on sound mass measurements, he also proposed the Law of Conversation of Mass.
http://cstl-csm.semo.edu/cwmcgowan/ch181/atomhist.htm -
Joseph Proust
proposed the the Law of Constant Composition.
http://cstl-csm.semo.edu/cwmcgowan/ch181/atomhist.htm -
John Dalton
Developed 1st atomic theory - Billiard Ball Model. Elements consisted of atoms. All atoms of an element are identical. Atoms of each element are different from one another. Compounds consisted of atoms are different elements combined together. Chemical reactions involved the rearrangement of combinations of those atoms.
http://www.barcodesinc.com/articles/timeline-on-atomic-structure.htm -
Gay-Lussac
Formulated the law that a gas expands linearly with a fixed pressure and rising temperature.
www.newworldencyclopedia.org/entry/Joseph_Louis_Gay-Lussac -
Michael Faraday
Studied the effect of electricity on solutions, coined term "electrolysis" as splitting of molecules with electricity. http://atomictimeline.net/index.php -
J. Plucker
Built one of the first gas discharge tubes ("cathode ray tube").
http://atomictimeline.net/index.php -
Dmitri Mendeleev
Arranged elements into 7 groups with similar properties. He discovered that the properties of elements "were periodic functions of the their atomic weights". This became known as the Periodic Law.
http://atomictimeline.net/index.php -
James Clerk Maxwell
Proposed the electomanetic theory - proposed that electic and magnetic fields filled the void http://www.geog.ucsb.edu/~jeff/115a/history/jamesclarkemaxwell.html -
Henri Becquerel
While studying the effect of x-rays on photographic film, he discovered some chemicals spontaneously decompose and give off very penetrating rays.
http://atomictimeline.net/index.php -
JJ Thomson
Plum Pudding model. Discovered the electron. Described atoms as ball of positive charge containing a number of electrons http://atomictimeline.net/index.php -
Marie Sklodowska Curie
Curie discovered radium and polonium and coined the term radioactivity after studying the decay process of uranium and thorium.
http://www.barcodesinc.com/articles/timeline-on-atomic-structure.htm -
Frederick Soddy
Soddy came up with the term "isotope" to explain the unintentional breakdown of radioactive elements.
http://www.barcodesinc.com/articles/timeline-on-atomic-structure.htm -
Nagaoka
Postulated a "Saturnian" model of the atom with flat rings of electrons revolving around a positively charged particle.
http://atomictimeline.net/index.php -
Philipp Lenard
Conducted Aluminum Foil Experiment. Found that a beam of electrons was able to pass through a sheet of aluminum foil with almost no deflection. Concluded that most of an atom's volume is just empty space. http://www.nobelprize.org/nobel_prizes/physics/laureates/1905/lenard-facts.html -
Richard Abegg
Abegg found that inert gases have a “stable electron configuration.
http://www.barcodesinc.com/articles/timeline-on-atomic-structure.htm -
Albert Einstein
Published the famous equation E=mc2. Created the Quantum Theory of Light - the idea that light exists as tiny particles called photons.
http://atomictimeline.net/index.php
http://www.aip.org/history/einstein/ -
Ernest Rutherford
He established that the nucleus was: very dense, very small and positively charged. He also assumed that the electrons were located outside the nucleus.
http://atomictimeline.net/index.php -
H.G.J. Moseley
Moseley discovered that the number of protons in an element determines its atomic number.
http://www.barcodesinc.com/articles/timeline-on-atomic-structure.htm -
Aston
Discovered the existence of isotopes through the use of a mass spedrograph.
http://atomictimeline.net/index.php -
Louis de Broglie
Discovered that electrons had a dual nature similar to both particles and waves. Particle/wave duality http://www.barcodesinc.com/articles/timeline-on-atomic-structure.htm -
Werner Heisenberg
Described atoms by means of formula connected to the frequencies of spectral lines. Proposed Principle of Indeterminancy "you can't know both the position and velocity of a particle.
http://atomictimeline.net/index.php -
Paul Dirac
Dirac proposed the existence of anti-particles.
http://www.barcodesinc.com/articles/timeline-on-atomic-structure.htm -
Glenn Seaborg
Seaborg discovered eight transuranium elements.
http://www.barcodesinc.com/articles/timeline-on-atomic-structure.htm -
Enrico Fermi
Enrico Fermi created the first man-made nuclear reactor.
http://www.barcodesinc.com/articles/timeline-on-atomic-structure.htm
