Rutherford's atom

Rutherford's atom: 
Experiment:

He beamed alpha particles through gold foil and detected them on a screen

If Thomson's model of atoms was correct, then the alpha particles should pass through with relatively little deflection

1. Most alpha particles (Helium atoms minus electrons) pass right through gold fold (its effect appears on the same position just before putting gold foil)

2. A small fraction of alphas are deflected very slightly

3. Some bounced back toward the source.

Conclusion:

1. Most of the atom is space not solid as Dalton and Thomson explained

2. The atom has very small part with very small volume but very high density (nucleus)

3.The most mass of the atom concentrate in the nucleus which has same charge of alpha particle (positive charge)

Rutherford's atomic model:

1. The atom: despite its extremely small size, it has a complicated structure that resemble (the sun) around which electrons (planets) orbit

2. The nucleus:

- Consists of positively charged particles called protons and neutral particles called neutrons

- Have a positively charges

- Much smaller than the atom; so:

          i.There is a vast space between the nucleus and the orbits of electrons

          ii.The atom is not uniformly dense because most of the atomic mass is concentrated in the nucleus

3.The electrons:

          Have negligible mass relative to that of nucleus

          Have a negatively charges

          Sum of its negatively charges of electrons = that of positively charges of nucleus, so the atom is electrically neutral

4.Electrons circle around the nucleus on special orbits at a tremendous speed despite the mutual attraction force between them and the nucleus because the attraction force is overcome by another force (centrifugal force) which is (equal it in quantity and opposite it in direction)

Objection on Rutherford's atomic model:

Rutherford's concept was contradicted by Maxwell's theory which based on laws of Newton mechanics and is concerned with the movement of relativity large bodies

Maxwell's theory: states that 

{when an electrically charged body moves in orbital, it will lose its energy gradually by emission of electromagnetic radiation (photons) causing gradual decreasing in orbit radius}

By applying this theory on Rutherford' atom:

Electron moving around the nucleus should emit an electromagnetic wave. That kind of emission leads to losing of its energy gradually

Electron should than move by helical motion and finally collide with the nucleus

In nature atom is stable and this terminating of the atomic system does not take place