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400
Democritus (400bc)
Contribution:Democritus used reasoning instead of science when he came up with his theory. He based his work on earlier philosophers. Democritus was the first person to suggest that materials were made up of smaller things. He called these ‘atomos’. He theorized that every material had its own type of atom and that no matter how small you cut something it would always have the same properties. He said the matter cannot be created nor destroyed.
SIgnificance: 1st to realize that their are atoms -
Period: 400 to
History Of The Atom
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Robert Boyle
Contribution: Boyle mainly studied gases. He discussed the possibility of atoms existing. He made gas chambers to study from. Unlike the greek philosophers, he was doing physical experiments. 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. He also was able to distinguish between a mixture and a compound. -
Issac Newton (1704)
Contribution:Newton studied gases, and the possibility of atoms existing, he proposed a mechanical universe in witch small solid masses were in motion. In short, he believed that there were little tiny pieces of mass that were ‘swimming’ everywhere.Significance:He began to understand that atoms or partials move and aren’t stationary. Life: Isaac Newton was born at near Grantham on 25 December 1642 and died on 20 March 1727. -
John Dalton
Contribution:Dalton did tones of research. He compiled it into what is now know as Dalton’s Theory. His theory contains 6 parts:1. Matter is composed of extremely small partials called atoms2. Atoms are indivisible and indestructible3. Atoms of a given element are different than those of other elements4. atoms of a specific element are different than those of other elements5. in a chemical reaction, atoms separate, combine and or rearrange -
Goerge Johnstone Stoney
Contribution:G.J Stoney proposed that electricity was made up of discrete negative particles he called "electrons."Significance: He was the first to propose the electrons existed although he did not prove that they did -
J.J Thompson
Contribution:Thomson created the cathode ray. The cathode ray is a tube that when a high voltage is sent through it and the atoms hit the outside of the tube and it glows. In this way, Thomson was able to test the polarity of the atoms by placing magnets next to the ray. He found that they were almost all negative. He also determined the charge to mass ratio Significance: He found the charge of Electons -
Albert Einstien
Contribution: Einstein was one of the greatest physicists and all round scientists of all time. In 1905 wrote 3 papers, each of these was the basis of new fields of physics. Einstein treated matter and energy as exchangeable. In 1905 he establishes his famous formula E=mc2 -
Errnest Rotherford
Contribution:Rutherford after many experiment found that:-An Alpha particle is positive -A Beta particle is negative -A neutral particle is light
Rutherford’s most famous experiment is the gold foil experiment, it consisted of shooting Alpha atoms into extremely thin gold foil and seeing where on the surrounding wall it hit. This found that their was an Nucleus in the inside of the atom -
Robert Millican
Contribution:Robert Millikan performed the ‘Oil Drop Experiment’ in witch he found and measured the electric charges in tiny falling water and oil. This study found that electrons existed and spent many years proving Einstein’s theory and was awarded the Nobel prize in 1923 Significance:He proved electrons exist and prove that there is a relationship between energy and frequency here is a link to the oil drop experiment
http://www.youtube.com/watch?v=XMfYHag7Liw -
Henry Mosley
Contribution:By using X-ray tubes, Moseley determines the charge of the nuclei of most atoms. He discovers that "the atomic number of an element is equal to the number of protons in the nucleus". This experiment helps him to create a more accurate version of the Periodic Table, reorganising it to base elements on atomic number instead of mass.Significance:He found the charge of the nuclei and corrected the periotic table -
Max Planck
Contribution: Max plank created the quantum theory.Significance:Max plank created the quantum theory. -
Neils Bohr
Contribution: Bohr found that electrons didn’t spiral into the nucleus, but orbit in different levels, this is called the Bohr/quantum model. He won a Nobel prize for his work, however when he first created it it wasn’t perfect and has been tweaked over the years.Significance: It gave us a better understanding of the structure of an atom, why atoms bond and they stay the same. -
louis de broglie
Contribution:His ideas were a basis for developing the wave mechanics theory. This theory has greatly improved our knowledge of the physical nature on the atomic scale. He received the Nobel Prize for Physics on his wave nature of electrons discovery in 1929.Significance: -
James Chadwick
Chadwick Discovered Neutrons. They differ from alpha rays because the repelled considerable electrical forces that are in the nucleus of many heavy atoms. A neutron can then penetrate as the nucleus of most elements.Significance:This advancement allowed for the fission of uranium, and the creation o very powerful bombs. -
Enrico Fermi (1938)
Contribution:Enrico Fermi was a physicist whose important discoveries about the atom led to the splitting of the atom (atomic bombs) and the using its heat into an energy source (nuclear energy). After Neurons were Found, Fermi came up with the idea to use neutrons, which have no charge, as projectiles. Fermi would shoot a neutron at a nucleus. many neurons were obsorbed but he slowed the speed and Split and atom
Significance: Invented Atomic Bomb and Nuclear Reactor
