Atomic Theory Timeline

By adnbet

  • Joseph Proust

    Joseph Troust introduced the law of constant composition which was highly controversial at the time.

  • Democritus

    Democritus was responsible for the first atomic theory. "He was considered to be the "father of modern science." His assertion was that the universe contained two elements. (And yes I realize that
    Democritus was not in 1800, it was 400 BC but this won't let me put that in.)

  • Aristotle

    Aristotle - Aristotle taught in approximately 600 B.C. that there were only four elements: fire, earth, air, and water and there was some "smallest part" of each of these elements but taught in direct contradiction to Democritus's teaching about the atom. Aristotle's teaching was generally more respected and accepted for thousands of years. (Also not in 1800 but 600 BC)

  • John Dalton and His Atomic Theory

    John Dalton discovers the Atomic Theory. His theory consists of four beliefs. 1.)All matter consists of tiny particles. 2.) Atoms are indestructible and unchangeable. 3.) Elements are characterized by the mass of their atoms. 4.) When elements react, their atoms combine in simple, whole- number ratios. This discovery is so important because without the atomic theory chemistry would be a nonuniform mess that we wouldn't understand.

  • Henri Becquerel and Natural Radioactivity

    Henri Becquerel discovered natural or spontaneous radioactivity, he was awarded half of the Nobel Prize in physics in 1903 for this discovery. He also did much work with phosphorescence and the polarization of light in his career.

  • J.J. Thomson and the Electron

    J.J Thomson discovered The electron in a series of experiments to study the nature of electronic discharge.The importance of Thomsons' discovery was that the electron went on to be a building block in chemistry the electron is very important and is tied into many things in chemistry. (Ernest Rutherford was Thomsons' student.)

  • Ernest Rutherford and Alpha and Beta rays

    Ernest Rutherford reported the existence of alpha and beta rays in uranium radiation and began to describe and identify some of their properties, in 1897 he worked with the concept of the mobility of ions in relation to the strength of the electric field and in 1900 helped discover radioactive disintegration

  • Paper Clip

    The paper clip was invented in 1899 Johan Vaaler.

  • Max Planck and the Quantum Theory

    Max Planck wrote the Quantum theory, in which he stated that light must be emitted and absorbed in small amounts he called this Blackbody Radiation. The importance of the quantum theory was to show that light is not continuous.

  • Stamps cost $0.02

    In 1900 a U.S stamp cost $0.02

  • Halley's Comet

    In 1910 Halley's comet is observed photographically for the first time

  • Robert Millikan and Electrons

    Robert Millikan - in 1910 Robert Millikan discovered and proved that electrons carried a negative charge.

  • Daylight Savings time

    In 1918 daylight savings goes into effect in March

  • Neils Bohr and his Atomic Model

    Neils Bohr discovered his atomic model. The importance of the discovery was to prove that atoms weren't just loosely put together they were put accordingly to how many electrons they had.

  • Whooping Cough Vaccine

    In 1922 a whooping cough vaccine is developed

  • Werner Heisenberg

    Werner Heisenberg discovered the uncertainty principal while measuring the location and momentum of electrons, realizing that the more accurately you are able to measure one the more you distort the measurement of the other as you interfere with its normal activity or location.

  • Louis de Broglie

    Louis de Broglie was awarded the Nobel Prize for physics for his discoveries concerning the wave nature of electrons, he also made many small discoveries concerning electrons which were included in his thesis in 1924 which where later confirmed by Davisson and Germer.

  • Pluto a Planet

    In 1930 astronomers discover Pluto as the ninth planet

  • Star Spangled Banner

    In 1931 the Star Spangled Banner becomes the official national anthem

  • James Chadwick and the Neutron

    James Chadwick discovered the neutron.Without his discovery we would not be able to look at elements the way we do. The neutron is like the electron it is so important and is another one of chemistry's building blocks. Without the neutron who knows where chemistry would be?

  • Erwin Schrodinger and his Equation

    Erwin Schrodinger discovered the Schrodinger equation. This equation described physical changes over time. This discovery was important because it showed that things don't stay the same over time they change and develop.

  • Vitamin K

    In 1934 Henrik Dam discovers Vitamin K

  • Antihistamine

    In 1937 a prototype "antihistamine" is produced to treat allergies

  • WWII

    WWII began on September 1, 1939