Periodic table

By dis922

  • The Skeptical Chemis

    Robert Boyle published "The Skeptical Chemist" which distinguished between the fields of chemistry and alchemy. The work also features some of the earliest recored ideas of atoms, molecules, and chemical reactions.

  • Hydrogen Discovered

    Hydrogen DiscoveredHenry Cavendish discoveries hydrogen. He describes it as a colorless, odorless gas that burns and can form an explosive mixture with air.

  • Oxygen Isolated

    Oxygen IsolatedCarl Wihelm Scheele and Joseph Pristly isolate oxygen.

  • First Elements

    First ElementsAntoine Lavoisier made the first extensive list of elements. The list featured 33 different elements and differentiated between metals and non-metals

  • Dalton's Law

    Dalton's LawJohn Dalton proposes "Dalton's Law" which describes the relationship between the different components in a mixture of gases. This discovery helps future scientists isolate a mixture of gases for individual study.

  • Periodic Table with Blanks

    Periodic Table with BlanksDmitri Mendeleev produces a periodic table based on atomic weights. This periodic table featured elements with similar properties being placed in groups under each other. This periodic table featured 66 known elements and had blank spaces for elements that he believed would be discovered in the future.

  • Elements Represented as Letters

    Elements Represented as LettersJakob Berzelius develops a table of atomic weights for several elements. This was the first table the represented different elements with letters.

  • Elements are Grouped

    Elements are GroupedJohann Dobereiner discovers that there are groups of three elements that have similar properties.

  • Valence Introduced to the Periodic Table

    Valence Introduced to the Periodic TableLothar Meyer develops a periodic table with 28 elements. The elements were organized according to valence.

  • Periodic Table Rearranged

    Periodic Table RearrangedJohn Newlands arranges the known elements in order of atomic weight and observes similarities between some elements.

  • Radioactive Elements Discovered

    Radioactive Elements DiscoveredMarie and Pierre Curie isolate radium and polonium.

  • Periodic Table Arranged by Atomic Number

    Periodic Table Arranged by Atomic NumberHenry Moseley determines the atomic number of each known element and rearranges the periodic table based on atomic number.

  • Neutrons Discovered

    Neutrons DiscoveredJames Chadwick discovers neutrons, which identifies isotopes. This demonstrated why there was a discrepancy between atomic number and atomic weight.

  • First Synthesised Element

    First Synthesised ElementEdwin McMillan and Philip H. Abelson identify neptunium, the first synthesized element. This was discovered in the products of uranium fission.

  • Lanthanides and Actinides1

    Lanthanides and ActinidesGlenn Seaborg identifies lanthanides and actinides (atomic number greater than 92) which are placed below the periodic table.