1.1 Fundamental Particles

1.1 Fundamental Particles

1. Development of ideas about the atom

   • 1661- Robert Boyle
     • Some substances could not be made simpler- chemical elements
   • 1803- John Dalton
     • Elements are made up from invisible atoms. Atoms in an element had same mass. atoms cannot be broken down
   • 1896- Henri Becquerel
     • Discovery of radioactivity. JJ Thompson- Discovery of the electron. Plum pudding model
   • 1911- Ernest Rutherford
     • Discovery of the nucleus. Knowledge of sub-atomic particles

2. Sub- atomic particles

   • Protons
     • Positively charged- +1
     • Found in the nucleus
     • Known as a nucleon
     • relative mass of approximately 1
   • Electrons
     • Negatively charged- -1
     • Found around the nucleus
     • Relative mass of 1/1800
   • Neutrons
     • No charge
     • Found in the nucleus
     • Known as a nucleon
     • relative mass of 1

3. Arrangement of the sub-atomic particles

   • Nucleus
     • protons and neutrons
       • held together by the strong nuclear force
   • Protons and electrons
     • held together by electrostatic forces
   • Electrons are arranged in sub-atomic shells