Discovery of the Neutron

Models throughout the years!!!!!

Our Model!

Sir James Chadwick Model

Sir James Chadwick

Discovery of the Neutron

Dalton's Atomic Model

Bibliography

By: Lizeth, Edgar, and Sydnie

Rutherford's Model

Question?

Bohr's Model

Do neutrons exist?

Scientist knew that there had to be something else in an atom because the atomic masses of the elements was an evidence for this. Scientist knew that electrons did not weigh much, but yet the atomic mass was high. From this Rutherford contributed the idea that there might be a particle giving mass but with no charge.

James Chadwick tried to prove Rutherford's idea.

"Atomic Structure Timeline." Atomic Structure Timeline. Lee Buescher, 2004-2013. Web. 04 May 2013. <http://www.atomictimeline.net/>.

"Chadwick Discovers the Neutron 1932." Pbs.org. A Science Odyssey, 1998. Web. 4 May 2013. <http://www.pbs.org/wgbh/aso/databank/entries/dp32ne.html>.

Crowell, Benjamin. "The Discovery of the Neutron." The Discovery of the Neutron. VIAS, 21 June 2009. Web. 04 May 2013. <http://www.vias.org/physics/bk2_05_05.html>.

McPhee, Isaac M. "The Discovery of the Neutron." Suite101.com. Suite101, 23 Jan. 2008. Web. 04 May 2013.

"The Neutron." Cambridge Physics. The Cavendish Laboratory, 2001. Web. 04 May 2013. <http://www-outreach.phy.cam.ac.uk/camphy/neutron/neutron1_1.htm>.

The idea that there might exist neutral particles in an atom was from Rutherford, which discovered the positively charged proton. Rutherford noticed that protons were not the only thing in the nucleus of an atom.

Was there another particle in the nucleus that nobody had yet discovered?

Pictures

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The Experiment............

Sir James Chadwick

The experiment was not conducted by Chadwick, but by Irene Joliot-Curie and her husband Frederic Joliot-Curie. A sample of Beryllium was bombarded with alpha particles and created a radiation that was then struck in a proton-rich surface. This released/discharged some of the protons.

Conclusion....

James Chadwick was born in Manchester, England on October 20, 1891. He attended the University of Manchester in 1908 and graduated from the Honours School of Physics in 1911. The next 2 years he worked with Ernest Rutherford in the Laboratory of Manchester. He earned his M.Sc. degree in 1913.

From this experiment Chadwick only had to arrange the puzzle and play a little with it to come to his conclusion. He noticed that the radiation was neutral because it was not affected when put close to a magnetic field, and unlike gamma radiation, it did not invoke the photoelectric effect (when photons, such as gamma rays, strike certain surfaces, they discharge electrons), but rather discharged protons.

James Chadwick officially discovered the neutron in 1932 and proved right Rutherford's theory that there was another particle in the nucleus of an atom. He also determined the weight of the neutron was 0.1% more than the proton's.

For his discovery, Chadwick won the Noble Prize for Physics in 1935

World War I

Chadwick was interned in Zivilgefangenenlager, Ruhleben until the war ended and returned to England to continue working with Rutherford in Cambridge.

Contribution to the Atomic Bomb

Chadwick was Head of the British Mission attached to the Manhattan Project to help develop the atomic bomb.