The History of Atoms and Elements

Timeline created by nkhara
  • 400

    Aristotle 384 BC - 322 BC

    Aristotle  384 BC - 322 BC
    "Without Evidence It Does Not Exist"
    In 400 BC Democritus theorized the existence of atoms. Aristotle disagreed and stated that the idea of atoms is worthless. Aristotle is not a scientist but a philosopher
  • 460

    Democritus 460 BC - 370 BC

    Democritus 460 BC - 370 BC
    "Old, Rejected, but Not Forgotten"
    Democritus brought about the idea that atoms existed. Democritus believed what’s left after breaking an object down until you can no longer break is the smallest bits of matter. He named them atoms. His idea was later shot down by Aristotle. Democritus is not a scientist because he did not do kind of scientific experiments. The theory he crafted was merely a result of a thought experiment.
  • Antoine Lavoisier 1743 - 1794

    Antoine Lavoisier 1743 - 1794
    "The True Iron Man"
    Antoine Lavoisier discovered the law of Conservation of Mass which he discovered by disproving an old theory about metal being calcined. He wrote the first list of elements containing thirty three elements, and also distinguished between metals and non-metals.
  • Humphry Davy 1778 - 1829

    Humphry Davy 1778 - 1829
    "The Discovery of more -iums"
    He discovered Potassium, sodium, calcium, strontium, barium, and magnesium. He discovered Potassium and sodium by electrolyzing slightly damp mashed potato and then soda. To discover the other elements he examined alkaline earths.
  • John Dalton 1766 - 1844

    John Dalton  1766 - 1844
    "Dalton and His Three Atoms"
    John Dalton proposed the Atomic Theory in 1803 which stated that all matter was made up of small indivisible particles called atoms, atoms of a given element possess unique characteristics and weight, and three kinds of atoms exist: simple , compound, and complex . John Dalton was a scientist because he was a meteorologist who later became a chemist. Meteorology and chemistry are both fields in science.
  • John Newlands 1837 - 1898

    John Newlands 1837 - 1898
    "The Prediction of Elements"
    John Newland invented the law of octaves, which state that if elements are ordered by atomic weight an element of similar physical or chemical properties will occur after seven elements.
  • J.J Thomson 1856 - 1940

    J.J Thomson 1856 - 1940
    "Thomson's Pudding"
    He discovered electrons, which he announced during one of his evening lectures to the Royal Institution on 1987. JJ Thomson's discovery of electrons led him to discover that the atoms can be split into smaller parts. JJ Thomson created the “Plum pudding model” , a sphere of positive charges filled with electrons. His discovery of electrons was a result of multiple experiments on high vacuum cathode ray tubes. In his experiments, the cathode rays bent over to one side.
  • Dmitri Mendeleev

    Dmitri Mendeleev
    "Atomic Weight and Element Behaviour"
    In 1869, Dmitri began the second volume to his book the Principles of Chemistry. Dmitri discovered that the behaviour of the elements seem to repeat as atomic weight increases.
  • Ernest Rutherford 1871 - 1937

     Ernest Rutherford 1871 - 1937
    "The Alpha Dog"
    Ernest Rutherford discovered the two types of radiation “alpha” and “male”. He also discovered that most of the total mass of an atom is concentrated into the nucleus. His discovery of the nucleus was a result of further experimentation on alpha particles and foil. He measured the fraction of the particle deflected through large angles which he then used to estimate the size of the nucleus.
  • Sir William Ramsay & Lord Raleigh

    Sir William Ramsay & Lord Raleigh
    "Ramsay's new gas in Raleigh's lab."
    In 1894, they discovered the first noble gas, argon. This established a new column in the periodic table. They discovered argon after working in separate laboratories on finding the hidden element while also communicating with each other about their results.
  • Robert Andrews

    Robert Andrews
    "The Charge of an Electron!"
    In 1910 , Robert Andrews measured the exact charge of an electron, and discovered that all electrons have the same charge.
  • Niel Bohr

    Niel Bohr
    In 1913, he discovered that atoms give off electromagnetic radiation. This theory was based on Ernest Rutherford’s model.
  • Henry Moseley

    Henry Moseley
    "Atoms and Waves"
    Henry Moseley discovered the relationship between wavelength and atomic mass through a series of tests involving the measuring of X-ray spectra of various chemical elements obtained by diffraction in crystals. He later published his results in 1913.
  • James Chadwick

    James Chadwick
    "What A Reaction!"
    In 1932, he discovered the neutron. He showed that in a reaction a neutral particle with the mass of a proton was released
  • Glenn Seaborg

    Glenn Seaborg
    "Glenn's Heavy Elements!"
    In 1942 - 1946, he showed how heavy elements form a transition actinide elements in a manner analogous to the rare-earth series of lanthanide elements. He is also the author of the anticide concept of heavy element electronic structure. He discovered this through arduous research and experimentation. The periodic table now shows how transuranium elements fit in.
  • Rutherfordium

    "Rutherford is not forgotton!"
    It was made in Russia using collision reactions between PU and NE ions. In 1969, American scientists created element 104 as well using the reaction between CF and C. The Americans stated that they were unable to reproduce the exact synthesis that the Russians created in 1964. They proposed the name Rutherford for the newly discovered element in honor of Ernest R Rutherford.