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400
Democritus (BC)
Location:Greece
Idea/experiment:Created a method for the formation of the universe
How this contributed to our understanding of the atom:Helped the development of the modern atomic theory
Source:http://www.atomictimeline.net/index.php -
Newton
Location:England
Idea/experiment:Thought the mechanical universe was with small solid masses in motion
How this contributed to our understanding of the atom:laid the base for differential and integral calculus
Source:http://www.atomictimeline.net/index.php -
Dalton
Location:England
Idea/experiment:An "atomic theory" with spherical solid atoms which was based upon measurable properties of mass.
How this contributed to our understanding of the atom:Helped with modern atomic theory
Source:http://www.atomictimeline.net/index.php -
G.J. Stoney
Location :Ireland
Idea/experiment:Proposed that electricity was made of discrete negative particles called electrons
How this contributed to our understanding of the atom:We now know that atoms are made up of electrons,protons and neutrons
Source:http://www.atomictimeline.net/index.php -
J.J. Thomson
Location:Britain
Idea/experiment:experimentally determined the charge to mass ratio of an electron coulombs/gram and Studied "canal rays"
How this contributed to our understanding of the atom:Thomson’s experiments and hypothesis meant that there was more experimental and theoretical work in other countries which lead to television and computers being developed and opened up a view of inside the atom.
Source:http://www.atomictimeline.net/index.php -
Planck
Location:Germany
Idea/experiment:used the idea of quanta to explain hot glowing matter
How this contributed to our understanding of the atom:Has helped modern theories and was a turning point in physics as it was the Quantum theory
Source:http://www.atomictimeline.net/index.php -
Nagaoka
Location:Japan
Idea/experiment:Hypothezised a "Saturnian" model of the atom with flat rings of electrons revolving around a positively charged particle.”
How this contributed to our understanding of the atom:Helped to complete a solution to atomic structure
Source:http://www.atomictimeline.net/index.php -
Milikan
Location:USA
Idea/experiment:Oil drop experiment determined the charge (e=1.602 x 10 -19 coulomb) and the mass (m = 9.11 x 10 -28 gram) of an electron.
How this contributed to our understanding of the atom:Led to studies of cosmic radiation and electrical phenomena and the law of motion
Source:http://www.atomictimeline.net/index.php -
E. Rutherford
Location:New Zealand
Idea/experiment:“He established that the nucleus was very dense, very small and positively charged. He also assumed that the electrons were located outside the nucleus. “
How this contributed to our understanding of the atom:Helped modern knowledge on atoms and the nucleus.
Source:http://www.atomictimeline.net/index.php -
H.G.J. Mosely
Location:Engand
Idea/experiment:He determined the charges on the nuclei of most atoms And wrote" The atomic number of an element is equal to the number of protons in the nucleus".
How this contributed to our understanding of the atom:His work was used to reorganize the periodic table based upon atomic number instead of atomic mass.
Source:http://www.atomictimeline.net/index.php -
Niels Bohr
Location:Denmark
Idea/experiment:“Developed an explanation of atomic structure that underlies regularities of the periodic table of elements.”
How this contributed to our understanding of the atom:His work helped other physicists to expand his theory into quantum mechanics
Source:http://www.atomictimeline.net/index.php -
James Chadwick
Location:England
Idea/experiment:Used alpha particles to discover a neutral atomic particle with a mass close to a proton, discovering the neutron.
How this contributed to our understanding of the atom:Modern atomic research has been helped by the knowledge Chadwick provided that there was a neutron.
Source:http://www.atomictimeline.net/index.php
