Rutherford's alpha Particle scattering experiment : Discovery of nucleus

Alpha particle:

Alpha particle is helium nucleus having 2 unit positive charge and 4 unit mass. Radioactive substances emit alpha particles continuously as alpha rays,

  Experimental setup:

A thin gold foil is taken and encircled by zinc suphide screen, Alpha particle is generated inside a lead box, A thin beam of alpha ray is passed on gold foil through a narrow slit. When alpha particles hit on gold foil, scattering occurs.

Scattered particles hit on zinc sulphide screen and produce flashes on the screen. it is observed by a microscope.  

Observations, conclusions and Ruthermord's  atomic model.

For the detailed study of observations, conclusions and Ruthermord's  atomic model,  watch on youtube. 

Thomson's atomic model

  After the discovery of electrons, J. J. Thomson put forwarded the atomic model to describe the occurrence of electrons inside the atom. He considered electrons are scattered inside the atom as seeds are scattered inside the watermelon. Electrons are negatively charged particles. The positive charge diffused on the atom neutralizes the negative charges of electrons. That's why it is called the watermelon model of the atom.