C3- periodic table

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early periodic table

  • during 19t century scientists had discovered elements but didnt know the structure of atoms
  • they classified the elements on their atomic weights and properties
  • Newlands preposed the law of octaves which said that every 8th element had similar properties
  • he arranged the elements into 7 groups due to atomic weight
  • other scientists didnt accept his ideas because the properties didnt match up
  • Mendeleev left gaps for undiscovered elements so groups of known elements did have similar properties
  • he predicted properties of missing elements
  • his table was the basis for the periodic table and was accepted by scientists because his predictions on properties were correct

modern periodic table

  • scientists found out about protons and neutrons at the start of 20th century
  • elements were arranged in periodic table by atomic numbers and lined in vertical groups
  • groups of elements have similar chemical properties because they have the same number of electrons in their outer shell
  • going…

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