Atomic Structure

Atomic Structure

1. 1.1 Fundamental particles

   • Developing idea of the atom!
     • The greek philosophers had a model in which matter was made up of a single continuous substance that produced the four elements- earth, fire, water and air. The idea that matter was made up of individual atoms was not taken seriously for another 2000 years. During this time alchemists built up a lot of evidence about how substances behave and combine. Their aim was to change other metals into gold. Here are a few steps that led to our present model.
       • 1661- Robert Boyle proposed that there were some substances that could not be made simpler. These were the chemical elements, as we now know them.
         • 1803- John Dalton suggested that elements were composed of indivisible atoms. All the atoms of a particular element had the same mass and atoms of different elements had different masses. Atoms could not be broken down.
           • 1896- Henri Becqueral discovered radioctivity. This showed that particles could come from inside the atom. Therefore the atom was not indivisible. The following year, J J Thomson discovered the electron