Chadwick and the Neutron

1. Chadwick and the Neutron By: Sophie Greenbaum and Ariel Silverman

2. Sir James Chadwick was born on October 20, 1891 in Bollington, Cheshire, England • He was the first child of John Joseph and Anne Mary Knowles Chadwick • He graduated from University of Manchester • Married in 1925 with twin girls James Chadwick James Chadwick

3. English physicist • After graduating, he was Rutherford’s coworker who took him to the Cavendish Laboratory at the University of Cambridge where he received his Doctor of Philosophy degree James Chadwick Education

4. Head of the British scientists who worked on the Manhattan Project during World War II • Knighted in 1945 for his accomplishments and achievements in Physics • He worked on many radio activity problems • He gained his M. S. C (Master of Science) degree in 1913 James Chadwick Achievements

5. Thompson discovered neon isotopes • Chadwick discovered the neutron • Thompson determined the ratio of the charge to mass e/m of the electron and that cathode rays consist of discrete particles of matter • Isotopes are different types of atoms of the same chemical element which each have a different number of neutrons • The neutrons explain the differences in weight The Connection of Thomson and Chadwick’s Discoveries J.J. Thomson

6. Chadwick discovered the neutron in 1932 • He noticed a inconsistency between the atomic numbers of atoms and the atomic weight • When they were studying atomic disintegration when they kept noticing that the atomic number was less than the atomic mass The Discovery

7. Chadwick came to the idea that there were two extra particles in a Helium atom • There were numerous reports of particles that turned out to be incorrect, many of Chadwick’s peers didn’t agree to his neutral particle theory • They assumed that the particles were actually Gamma rays (neutral, high energy photons) • Chadwick then went out and tried to prove that the neutral radiation had mass • The neutral radiation needed to have the same masses The Discovery

8. Chadwick put a piece of beryllium in a vacuum chamber with some polonium • The polonium set out alpha rays which struck the beryllium and they gave out neutral rays • He put a target in the path of the rays and when they hit the target they knocked atoms out of it • These atoms became electrically charged and they flew into a detector filled with gas • Passing through the chamber, it ionized the gas molecules and it drifted toward an electrode • The explanation for all his results was a neutral particle which is the neutron The Discovery

9. Subatomic particles that have n or n0 symbol • No electric charge and its mass is a little bit more than a protons • Necessary within an atomic nucleus • Discovered in 1932 • In 1932,Chadwick it might cause a nuclear chain reaction • The main role of the neutrons in the nucleus of an atom is to add to the binding energy that holds the nucleus together • In order to overcome the forces of the protons, neutrons are included in the structure The Neutron

10. James Chadwick contributed to atomic theory by his experiments and observations proving and discovering the neutron • He won the Nobel Prize in 1935 for this discovery Chadwick’s Part in the Development of the Atomic Theory

11. WORKS CITED: • http://www.nature.com/physics/looking-back/chadwick/index.html • http://www.pbs.org/wgbh/aso/databank/entries/dp32ne.html • http://www.biography.com/people/jj-thomson-40039 • http://www.famousscientists.org/james-chadwick/