Rutherford’s α – scattering experiment concludes that

CONCEPT:

• Rutherford’s Model of the Atom: He bombarded the beam of alpha particles on a very thin gold foil.

While bombarding he observed the number of scattering particles:

• Most of the particles passed either un-deviated or with a very small deviation and very few deviated by large angles
  • 1 out of 8000 was deflected by more than 90°
• The conclusion to this deflection:
  • Most of the space of an atom is empty and at the center of an atom having a tiny positively charged particle called a nucleus.
  • The center nucleus has all the mass of an atom and all the electrons revolve around the nucleus and the Coulomb force provides the centripetal force.

EXPLANATION:

• Some of the alpha particles directed at the nucleus were deflected heavily away.
• It was concluded that heavy mass at the center of the atom is responsible for the large-scale scattering of alpha particles. 
• The negatively charged electron revolves around the nucleus of the atom. So option 3 is correct. 

Limitations of Rutherford’s Model of the Atom:

• As Rutherford’s Model suggests electrons always revolve around the nucleus.
• From the point of mechanics, it is okay as Coulomb's force provides the necessary centripetal force.
• But according to Maxwell’s equation of electromagnetism, this revolving electron continuously emits radiation at all temperatures.
• This energy spends ultimately makes an electron fall on the nucleus. But in real case hydrogen is very stable nor does it emit any energy.