The Periodic Table

The Periodic Table

1. The atomic model

   • Demitri Mendeleev
     • Dmitri was a Russian scientist who made the periodic table how we know it now
       • In 1869, he discovered that the chemical and physical properties of elements were related to the mass and ordered the elements in groups of similar properties in a table.
         • He arranged the known elements of that time in the order of their relative atomic mass but left gaps knowing they were just elements that were yet to be discovered
           • He worked out the atomic mass of the missing elements in the table and later he turned out to be right when they were discovered.
   • Daltons 'Plum pudding' model
     • John Dalton proposed that all matter is composed of very small things which he called atoms
       • The atom was imagined to be a sphere of positive charge with negatively charged electrons dotted around inside it like plums in a pudding.

2. Electronic configuration

   • Electrons are found around the atom in shells
     • The lowest energy levels are always filled first
       • Only a certain amount of electrons are allowed in each shell: First shell is 2, second shell is 8 and third shell is 8

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