The Atom

The Atom

1. 1 - Democritus

   • Suggested that matter cannot be cut into smaller pieces
   • gave a name to the smallest
   • Particle of matter: The Atom
   • Ancient Greek philosopher

2. 2 - John Dalton

   • Model was very small, indestructible sphere
   • - all atoms in an element are the - atoms in one element are different from the atoms in another element

3. 3 -Joseph Thomson

   • Plum pudding model
   • Thought the atom was like a positively charged ball with electrons moving around inside hen all like raisins in a Christmas pudding

4. 4 - Ernest Rutherford

   • Thought positive charge was concentrated at the centre of the atom, he called the nucleus
   • His model is sometimes called the planetary model because it looks like a mini solar system

5. 5 - Neil Bohr

   • Idea was that electrons were arranged at discrete energy levels around the nucleus

6. 4 - Geiger and Marsden

   • Rutherford's students
   • most alpha particles passed straight through the gold foil, deflected by no more than a few degrees
   • small fraction of the alpha particles were actually reflected back towards the direction from which they had come