JAMES CHADWICK

WHO IS HE?

• Born in England on October 20 1891 and died July 24 1974
• Went to Victoria university of Manchester where he went to study Mathematics but enrolled in physics by mistake.

HIS CONTRIBUTION

• Famous for his discovery of the neutron.

CHADWICK AND THE NUETRON

• In 1932 he made a fundamental discovery in the domain of nuclear science.
• He discovered the the particle in the nucleus of an atom that became known as the neutron due to the fact that it has no charge.

THE NEUTRON

• Because the neutron has no electrical charge this is why it was not discovered earlier.

THE NEUTRON

• The existence of neutrons explained why atoms were heavier than the total mass of the protons and electrons.

HIS REASONING

• His reasoning was the mass of the atom is greater than the mass of its protons and electrons. Therefor there must be another particle in the atom.
• This additional particle must not have a charge, because if it had charge then the atom would not longer be electrically neutral.

THE EXPERIMENT

• In 1930, when Herbert Becker and Walter Bothe sent Alfa particles against beryllium, strong penetrating radiation was emitted, there was a hypothesis that this could be electromagnetic radiation of high energy.
• In 1932, it was James Chadwick that would show in the reaction, a neutral particle with the mass of a proton was emitted.

THE EXPERIMENT

• Projected Alfa particles (two protons and two neutrons bound together) and when the Alfa particles reached the beryllium (a chemical element with the atomic number 4) the beryllium became neutrons and fell off on paraffin wax.

Untitled Slide

CHADWICK AND THE NEUTRON

• In 1935 he was awarded the Nobel prize for this discovery.