history of the atom

• describe the plum pudding model and who created it ?

  JJ Thompson created the plum pudding model- it was a circular ball of posotive charge with mas distributed across it , there where small electrons dotted around within the sphere.
• who discoverd shells and why are they needed ?

  neils bohr discovered shells which was in response to rutherfords model. bohr claimed that the shells where needed to contain the electrons because if they where free to move as in rutherfords model then the opposite charges would attract collapsing the atom
• who discovered the neutron?

  james chadwick
• who invented and what was the first model of the atom?

  the first model of the atom was created by jhon dalton and it was the theory that everything was made up of small spheres thats it
• who discovered protons ?

  later aftyer bohrs model rutherford discovered the existance of the proton
• in the 1800's how where elements arranged?

  in order of atomic weight
• who what why and when did the periodic table change ?

  Dimitri Mendeleev changed the periodic table in 1869. the major changes he made where moving elements based on properties and predicting elements by leaving gaps in the table