Question

explain Rutherford alpha scattering experiment

Answer 1

1.An atom consists of two parts known as nucleus and extra nuclear portion.
2.Nucleus is present in the centre of the atom.It is massive +vely charged and extremely small on size about 10^-15m
3.The +ve charge is due to the protons.
4.Extra nuclear portion is the space around the nucleus in which all the electrons are present.
5.Total +ve charge on the nucleus is equal to the-ve charge on the electrons.
6.electrons in the extra nuclear portion are not stationary but revolving around the nucleus at high speeds in circular paths called orbits.

Answer 2

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»Rutherford bombarded a thin gold foil with high speed alpha particles which are obtained from radioactive material

»Alpha rays are made to travel in straight lines by passing them through Lead sheets having holes at their centres .zinc sulphide screen was placed behind the gold foil to know the position of the alpha rays .

Rutherford observed that :

most of the Alpha particles passed without any deflection

some of them were deflected away from their path

only a few were returned back to their original direction of propagation

Rutherfords atomic model:

the main features of this model are

atom is Spherical and hollow

the total mass and total positive charge is concentrated in a small region at the centre part of the atom which is called in nucleus

this model is called solar Model or planetary model

electrons and nucleus are held Together by electrostatic force of attraction

Drawbacks:

As per electromagnetic theory the revolving electron should lose energy continuously and travel in a spiral path and finally should fall into the nucleus so atom should collapse but atoms are stable