By Pfeifa
  • Period: 450 to


  • 460


    Democritus was born in Greece 460 BC He was the first person to claim that all matter is made up of atoms; atoms cannot be physically separated from each other, there is, empty pace between each atom, they are indestructible, they are always in motion and that there is an infinite number of atoms and kinds of them which can be all shapes and sizes. Democritus started “The more any indivisible exceeds, the heavier it is.”
  • Antoine Lavoisier

    Antoine Lavoisier
    Antoine Lavoisier was the scientist who proved the law of conservation of mass in1789. The law of conservation of mass sais that mass be created or destroyed and that the mass of products must equal the mass of reactants. Also Antoine Lavoisier proved that when oxygen and hydrogen combine, water is formed from them.
  • Joseph Proust

    Joseph Proust
    Joseph Proust published his Law of Definite Proportions or Law of Constant Composition, in 1794. The Law of Definite Proportions states; a compound is made up of exact proportions of elements by mass, regardless of which way the compound was created. For example to make water, there has to be a specific ratio of grams of hydrogen to oxygen regardless of where the water is from.
  • John Dalton

    John Dalton theory on the principle that atoms of different can be distinguished by the differences in their weight. All matter is composed of atoms.Atoms can’t be created or destroyed.Atoms of the same elements are all identical.Different elements have different types of atoms.When atoms are rearranged, chemical reactions occur.
    Compounds are formed from atoms of essential or basic elements.
  • Wilhelm Roentgen

    Wilhelm Roentgen
    Wilhelm Roentgen was a German physicist he was born in1845 and died in 1923 He accidentally discovered x rays in 1895 and this dramatically changed the fields of medicine and physics. This also helped to prove the existence of electrons in atoms. An x-ray is a type of radiation, which can penetrate materials that light isn't able to. For this he first ever Nobel Prize
  • Max Plank

    Max Plank
    Max Plank German Physicist, born on the 23rd of April 1858 to the 4th of October 1947. The quantum of action, which is now known as Planck’s constant h. He explained energy isn't a continuously flowing unit, but it is carried in smaller irregular units. He called these ‘quanta’. His theory was called, ‘The Law of Energy Distribution in the Continuous Spectrum.
  • JJ Thompson

    JJ Thompson
    In 1897, JJ Thompson discovered the electron. His work was the birth of the theory that atoms are made up of small particles. His theory was proved using a cathode ray tube. Doing this he discovered that there were smaller particles than an atom, electrons. It was then proved that atoms were made up of protons, electrons and neutrons.
  • Robert Millikan

    Robert Millikan
    JJ Thompson’s hypothesis a singles electron was at least 1000 times less than the smallest atom.Robert Millikan measured the charge on an electron using an oil drop apparatus. Oil droplets were sprayed onto a sample chamber and some droplets would fall through a pinhole into an area between a positively charged plate and a negatively charged plate, which was ionized by x-rays. Particles that didn’t capture electrons fell to the bottom and the ones that did capture electrons rose to th
  • Antonius Johannes Van Den Broek

    Antonius Johannes Van Den Broek
    Antonius Johannes Van Den Broek was born on the 4th of May 1870, and died on the 25th of October 1926. He was a Dutch amateur physicist who was the first person to realize in 1913, that the number of an element on the periodic table matches the charge of its atomic nucleus.
  • Ernest Rutherford

    Ernest Rutherford
    Ernest Rutherford was born 30th of August 1871 and he died on the 19th of October 1937. In 1907 Ernest Rutherford, Hans Geiger and Ernest Marsden attempted to examine the structure of an atom using the Geiger-Marsden experiment. The results demonstrated the existence of the atomic nucleus and it then was an important part of the Rutherford model of the atom. The Rutherford model of the atom is the one where it shows electrons circling the nucleus.The element ‘rutherfordium’, was
  • Niels Bohr

    Niels Bohr
    Niels Bohr was a Danish physicist who was born in 1885 and died in 1962. Niels Bohr’s main goal was to research the structure of the atom and in 1913; his theory of the atomic structure was complete. His theory was a mixture of both Ernest Rutherford’s work and Planck’s Quantum Theory. Bohr declared that an electron could orbit the nucleus, but it could only do this in discrete orbits, which didn’t release any radiation.
  • Erwin Schrodinger

    Erwin Schrodinger
    Erwin Schrodinger an Austrian physicist, born on the 12th of August 1887 and he died on the 4th of January 1961. He developed a powerful atomic model in 1926. For the distribution of electrons in an atom, he combined the de Broglie equation to generate a mathematical model. The model contains wave functions (mathematical equations) to fulfil the needs placed on the behaviour of electrons. The disadvantage of this model is that it is hard to think of a physical model of electrons as waves.
  • Henry Moseley

    Henry Moseley
    Henry Moseley was a British chemist who was born on 1887 to 1915. Ernest Rutherford and himself developed the submission of x-ray fields to study the atomic structure. As a result of Moseley’s discoveries, aperiodic table with more accurately positioned elements was produced by closer determination of atomic numbers. This showed that the ordering of the wavelengths of the x-ray secretions of the elements, matched the orders of the elements by their atomic number. This was the disco
  • James Chadwick

    James Chadwick
    James Chadwick October 20th 1891 and he passed away July 24th 1974. James Chadwick discovered the neutron by using some work from Irene Joliot Curie. James knew that it wasn’t caused by either electric or magnetic fields, and he figured that it was contained neutral particles, neutrons.
  • Louis De Broglie

    Louis De Broglie
    Louis De Broglie was a French quantum physicist who was born on the 15th of August 1892 and died on the 19th of March 1987. In 1924 he had a theory of wave duality. He had seen that instead of light matter being against one another, waves or ‘radiation’ can behave like particles and particles can behave like waves. His theory helped to explain the theory of wave functions, by Erwin Schrodinger.