Timeline of Atomic & Quantum Theory PDF

Timeline of atomic Theory / Quantum Theory Time Scientist Discovery 400 BCE Democritus - Everything is composed of atoms - Between atoms there are empty space - Atoms are indestructible and indivisible...

Timeline of atomic Theory / Quantum Theory Time Scientist Discovery 400 BCE Democritus - Everything is composed of atoms - Between atoms there are empty space - Atoms are indestructible and indivisible - There is an infinite number of atoms 350 BCE Aristotle Though all the materials on earth were not made of atoms, but rather they were made of the four elements, Erth, Fire, Water, and Air. he believed everything was made of small amounts of these four elements of matter. 1807 John Dalton He proposed an "atomic theory" with spherical solid atoms based upon measurable properties of mass. 1832 Michael He also suggested that atoms also have negative charge in them.discovery was crucial in allowing electricity to be Faraday transformed from a curiosity into a powerful new technology. 1811 Amedeo Equal volumes of different gasses contain an equal number of molecules, if they are the same temperature and the same Avogadro pressure. First scientist to realize that elements could exist in the form of molecules instead of individual atoms 1869 Dmitri He created the first periodic table. It states that when elements are arranged according to their Mendeleev atomic number, elements with similar properties will appear at regular intervals. 1879 William - Reconstructed the Cathode Ray. - Discovered the element thallium Crookes - He showed that there is negative charge in atoms 1886 Eugen When the cathode of the cathode ray perforated, he observed the rays and called it canal rays, which passed Goldstein through the holes, or channels, in the cathode to strike the glass walls of the tube at the end near the cathode. Since these cathode rays travel in the opposite direction from the cathode rays, they must carry the opposite charge. 1897 JJ Thomson - Discovered the electron by experimenting with a Cathode Ray - He demonstrated that Cathode rays were negatively charged - He also studied positively charged particles in neon gas 1900 Max Planck Known as the originator of Quantum Theory of energy, for which he was awarded the Nobel peace prize in 1981. 1911 Earnest He was the first to discover that atoms have a small charged Rutherford nucleus surrounded by largely empty space, and are circled by tiny electrons, which became known as the Rutherford model (or planetary model) of the atom. He is also credited with the discovery of the proton in 1919, and hypothesized the existence of the neutron. 1913 Niels Bohr Proposed a theory for the hydrogen atom based on the Quantum theory; energy is transferred only in certain well defined quantities. Electrons move around the nucleus but only in prescribed orbits, and when jumping from one orbit to another with lower energy, light quantum is emitted. 1905 Albert He proved the theory of max planck’s by the method of Einstein photosynthesis. That black body absorbs EM radiation. 1923 Louis de In his 1924 thesis, he discovered the wave nature of electrons Broglie and suggested that all matter have wave properties.  1925 Wolfgang Wolfgang Pauli was an Austrian theoretical physicist noted Pauli for his work on spin theory and quantum theory, and for the important discovery of the Pauli exclusion principle, which underpins the structure of matter and the whole of chemistry. 1927 Werner He devised a method to formulate quantum mechanics in Heisenberg terms of matrices 1930 Erwin A noted theoretical physicist and scholar who came up with a Schrodinger groundbreaking wave equation for electron movements. 1932 James A British physicist who was awarded the 1935 Nobel Prize in Chadwick Physics for his discovery of the neutron in 1932. Electronic configuration