3.1.1.1 Fundamental Particles

scientists that contributed to the theories and models of an atom:

• John Dalton (1803)

  • suggested that matter is made up of atoms, which are indivisible and cannot be destructed

  • introduced idea that atoms of different elements have different masses

• JJ Thompson (1897)

  • he discovered the electron ( a tiny negatively charged particle)

  • PLUM PUDDING MODEL: it was initially thought that atoms consisted of a sphere of positive charge, with small negative charges distributed evenly within it

• Ernest Rutherford (1909)

  • he conducted the gold foil experiment which showed that atoms have a smaller dense centre called the nucleus

  • contains most of the atom’s mass, with electrons orbiting around it

• Neil Bohr (1913)

  • improved Rutherford’s model by saying that electrons orbit the nucleus in specific paths or energy levels and they can jump between these levels by gaining or losing energy

• James Chadwick (1932)

  • he discovered the neutron