Periodic Table Timeline

  • 400


    Greek philosopher who developed one of the first atomist theories of the universe. Democritus believed that the world consists of an infinite
  • sir francis bacon

    Sir Francis Bacon published "The Proficience and Advancement of Learning" which contained a description of what would later be known as the scientific method.
  • Robert Boyle

    Defined an element as a substance that could not be broken down into a simpler substance by a chemical reaction.
  • Dimitri Mendeleev

    periodic table was first published by Dmitri Mendeleev in 1869.The elements carbon,sulfur,iron,tin,lead,copper,mercury,silver,and gold and known to humans since ancient time.
  • Henry Cavendish

    He was the first to recognize hydrogen gas as a distinct substance for which he calculated their densities as well as the densities of several other gases
  • Lother Meyer

    In 1864, five years before the first announcement of a Periodic System by Mendeleev, Meyer had produced a table of just 28 elements which he listed by their valence. [The term valence is now called valency and represents ‘combining power’ of an element. For example sodium forms a chloride NaCl and has a valency of one; magnesium forms MgCl2 and has a valency of two and so on.] The 28 elements were almost entirely main group elements. He was well known
  • Jacob Berzelius

    Before the early 1800s the symbols used to denote chemical elements and compounds were obscure. Alchemists wanted to keep their work secret and so devised symbols for the chemicals they used that would not reveal anything about them. This all changed with the work of Jöns Jakob Berzelius.
  • Earnest Rutherford

    1886 - Ernest Rutherford named three types of radiation: alpha and beta and gamma rays.
  • Henry Moseley

    Henry Moseley was an outstandingly skilled experimental physicist. In 1913 he used self-built equipment to prove that every element’s identity is uniquely determined by the number of protons it has. His discovery enabled him to predict confidently the existence of four new chemical elements, all of which were found
  • Antoine Lavoiser

    Lavoisier defined an element as any substance which could not be decomposed into simpler substances. Several of the elements he lists in his introductory chemistry text are now known to be compounds. Two of his elements (heat and light) are not considered matter at all. Lavoisier anticipated that his list was necessarily limited to an 18th century perspective,
  • Marie Curie

    SCIENTISTS HAD IDENTIFIED over 60 elements by Mendeleev's time. (Today over 110 elements are known.) In Mendeleev's day the atom was considered the most basic particle of matter. The building blocks of atoms (electrons, protons, and neutrons) were discovered only later. What Mendeleev and chemists of his time could determine, however, was the atomic weight of each element: how heavy its atoms were in comparison to an atom of hydrogen, the lightest element.
  • William Ramsay

    Sir William Ramsay was an eminent British physical chemist who is credited with the discovery of argon, krypton, neon and xenon. He also demonstrated that these gases, along with helium and radon, makes the noble gases; a family of new elements. Ramsay won the 1904 Nobel Prize in Chemistry for his extraordinary efforts.
  • John Newlands

    Newlands' Periodic Table. An English scientist called John Newlands put forward his law of octaves in 1864. He arranged all the elements known at the time into a table in order of relative atomic mass. When he did this, he found that each element was similar to the element eight places further on.
  • Aristotle

    Greek philosopher; pupil of Plato, tutor of Alexander the Great, and founder of the Peripatetic school at Athens; author of works on logic, ethics, politics, poetics, rhetoric, biology, zoology, and metaphysics. His works influenced Muslim philosophy and science and medieval scholastic philosophy