The Periodic Table

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  • The Periodic Table
    • The Early Periodic Table
      • in the 19th century (1800) less than 40 elements had been discovered.
      • New ones were being discovered regularly
      • The scientists started to see a pattern in the way the elements reacted
      • One of the first scientists to publish a version of the table was a English scientist called John Newlands
        • he arranged them in 'law of octaves'
          • he noticed that every 8th element had similar properties.
          • The law of octaves only worked for the first few elements.
        • left out that there were more elements to be discovered.
      • Scientists worked out properties like the atomic mass.
      • A Russian scientist Dmitri Mendeleev arranged the elements in periodic way.
        • he left gaps where he thought new elements would be discovered.
        • he predicted the atomic masses and other properties of undiscovered element's
        • No group 0 as the noble gasses hadn't been discovered yet
    • The Modern Periodic Table
      • More elements were discovered
        • We order the elements today with the atomic number
        • the elements in the same group have similar properties.
        • middle block are is the transition metals
          • compared to group 1 they have
            • a higher melting and boiling point (except for mercury)
            • they are harder and stronger
              • good to be used for structural materials
            • are much less reactive and so don't react so much with water and oxygen
          • they can form ions with different charges
          • they form coloured comounds
          • they are useful as catalysts
      • the groups are arranged by the number of electrons on their outer shell.
        • Group 0 have a full outer shell of electrons
        • Group 1 are the Alkali metals
          • Low density
          • React with non-metals to form ionic compounds
            • will produce a ion with a +1 charge
          • React with water to produce hydrogen
          • The further down the group you go:
            • the lower the melting and boiling point
            • the more reactive the element

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