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400
Deomeas
Wikipedia IndexDate: 460-370 BC
Location: Greece
Idea/Experiment: Continued the work of his mentor, Leucippus Formulated an atomic theory similar to modern science’s understanding of the atom How this contributed to our understanding of the atom: His theory suggested that atoms can’t be destroyed and exist in a void. Atoms only differ in shape, position and arrangement. -
Period: 400 to
Life of Atom
the basic unit of a chemical element. -
John Dalton
Science World Biography: Dalton- John DaltonDate: 1803
Location: England
Idea/Experiment: He proposed an atomic theoryHow this contributed to our understanding of the atom: Dalton stated (1) all matter was composed of small indivisible particles termed atoms, (2) atoms of a given element possess unique characteristics and weight, and (3) three types of atoms exist: simple (elements), compound (simple molecules), and complex (complex molecules). -
Dmitri Mendeleev
Dmitri Ivanovich Mendeleev: Dmitri MendeleevDate: 1869
Location:Tobolsk
Idea/Experiment:In 1863 there were 56 known elements with a new element being discovered at a rate of approximately one per year. Other scientists had previously identified periodicity of elements. John Newlands described a Law of Octaves, noting their periodicity according to relative atomic weight in 1864, publishing it in 1865. His proposal identified the potential for new elements such as germanium. The conce -
J.J Thomson
Wikipedia- J. J. ThomsonScience World Biography: ThomsonDate:1897
Location: England
Idea/Experiment: The discovery of the electron and of isotopes, and the invention of the mass spectrometer.How this contributed to our understanding of the atom: With the Nernst-Thomson rule he explains that it is difficult for charged ions to attract each other through insulating water molecules, so they dissociate. -
Ernest Rutherford
Science World Biography: Rutherford- Ernest RutherfordDate:1911
Location: Britain/New Zealand
Idea/Experiment: Rutherford was a chemist and physicist who was known to be the father of nuclear physics.How this contributed to our understanding of the atom: Rutherford discovered the concept of the radioactive half life. He also differentiated and named alpha and beta radiation. Rutherford is credited for performing the first splitting of an atom. -
Neils Bohr
Crystalinks: Neils BohrLucid Cafe Library: Neils BohrDate: 1922
Location:Denmark
Idea/Experiment: Fundamental contributions to the understanding of atomic strucutre and quantum mechanics.How this contributed to our understanding of the atom: By expanding on Rutherford's earlier theory, Bohr published his theory which suggested that electrons travel in specific orbits around the nucleus, that outer orbits can hold more elctrons than the inner orbits and that these orbits determine the chemical -
James Chadwick
Nobelprize: James Chadwick- James ChadwickDate: 1932
Location: England
Idea/Experiment: Famous for his discovery of the neutron/How this contributed to our understanding of the atom: Chadwick discovered the neutron, named because of its lack of electrical charge, which was previously an unknown particle in the nucleus of an atom. -
Murray gell mann and George Zweig
Wikipedia: George Zweig Murray Gell-Mann
Location:New York City/ Moscow
Idea/Experiment: Murray Gell-Mann and George Zweig tentatively put forth the idea of quarks. They suggested that mesons and baryons are composites of three quarks or antiquarks, called up, down, or strange