I would like to thank my science teacher Shalini Mam and my parents for helping me in making this presentation. My parents

helped me in editing of this presentation. They also helped me in formatting the matter of the presentation. I collected the information from the internet and from some books.My other gratitude I would like to convey to my school who suggest me to make this and to have marks for adding it into examination.

Ernest Rutherford (1871-1937)

Ernest Rutherford, first known as Baron

Rutherford (30 August 1871-19 October

1937) was a New Zealand-born British

chemist and physicist who became

known as the father of nuclear

physics. He is considered the greatest

experimentalist since Michael

Faraday (1791–1867). In early work he

discovered the concept of

radioactive half-life, proved that

radioactivity involved the

transmutation of one chemical element

to another, and also differentiated and

named alpha and beta radiation.

This work was done

at McGill

university in Canada.

It is the basis for

the Nobel Prize in

Chemistry he was

awarded in 1908 "for

his investigations

into the

disintegration of the

elements, and the

chemistry of

radioactive

substances ”.Structure of an Atom

Rutherford scattering experiment is a phenomenon in physics that was explained by Ernest Rutherford in 1911, which led to the development of the Rutherford

model (planetary model) of the atom, and eventually to the Bohr Model. It is now exploited by the materials analytical technique Rutherford Backscattering. Rutherford scattering is also sometimes referred to as Coulomb scattering because it relies only

upon static electric (Coulomb) forces, and the minimal distance between particles is set only by this potential. The classical Rutherford scattering of alpha particles against gold

nuclei is an example of "elastic scattering" because the energy and velocity of the outgoing scattered particle is the same as that with which it began.

Rutherford also later analyzed inelastic scattering when he

projected alpha particles against hydrogen nuclei (protons) ; however this latter process is not referred to as "Rutherford scattering", although Rutherford was first to observe it. At the end of such processes, non-coulombic

forces come into play. These forces, and also energy gained from the scattering particle by the lighter target, change the

scattering results in fundamental ways which suggest structural information about the target. A similar process

probed the insides of nuclei in the 1960s, and is called deep inelastic scattering.

¡Gold Foil¡Lead Block Shield¡Zinc Sulphide Screen¡Source of Alpha particles

A narrow beam of alpha particles was

aimed at a thin sheet of gold foil.A zinc sulfide coated screen surrounding the

gold foil produced a flash of light when struck

by an alpha particle (radioactive materials

expose photographic film).By noting where the flashes occurred, the

scientists could determine if the atoms in the

gold foil deflected the alpha particles.

§ Most of the particles went straight through the gold foil

§ Several particles were deflected straight back toward the source!

§ A few particles were deflected at large angles.

INTERPRETING THE OBSERVED DEFLECTIONS

*****

****

*****

gold foil

Deflected particle

Undeflected particles

*

* Beam ofalpha particles*

As a result of his observations, Rutherford suggested that the atom had a positively charged centre which contained most of the mass.he called the heavy positively charged centre the nucleus.he went on to suggest that the nucleus was surrounded by orbiting electrons required for electrical neutrality.

The major drawback of Rutherford’s

model of an atom is that it does not explain

the stability of the atom.

In the Rutherford’s model of an atom, the

negatively charged electrons are revolving around

the positively charged nucleus in circular paths.

Now, we know that if an object moves in a circular

path, then its motion is said to be accelerated. This

means that the motion of an electron revolving

around the nucleus is accelerated.

If we apply this electromagnetic

theory to the Rutherford’s model of

an atom, it will mean that the

negatively charged electrons

revolving around the nucleus with

accelerated motion , will lose their

energy continuously by radiation.

Thus, the energy of revolving

electrons will decrease gradually

According to the electromagnetic theory of

physics, if a charged particle undergoes

accelerated motion, then it must radiate energy

(or lose energy) continuously.

and their speed will also go on decreasing. The electrons will

then be attracted more strongly by the oppositely charged

nucleus due to which they will come more and more close to

the nucleus. And ultimately the electrons should fall into the

nucleus by taking a spiral path. This should make the atom

very unstable and hence the atom should collapse.