Ernest Rutherford & the Gold Foil Experiment

1. Ernest Rutherford& the Gold Foil Experiment By Jake Easton & James Lampmann

2. Birth • He was born on August 30, 1871 in Nelson, New Zealand • His parents were James and Martha Rutherford • He was one of 12 kids

3. Education • In 1887, he won a scholarship to Nelson College • From 1890 to 1893, he attended Canterbury College at the University of New Zealand • In 1894 he received an 1851 Exhibition Science Scholarship which allowed him to go to the Trinity College, Cambridge. • While he was there he studied as a research student under J.J. Thompson at the Cavendish Laboratory.

4. Jobs/ Career • In 1897 the MacDonald Chair of Physics at McGill University in Montreal, Canada became open. In 1898 he left New Zealand to take the job. • In 1907 he returned to England to become the Langworthy Professor of Physics at the University of Manchester • In 1919, he took a job as a Cavendish Professor of Physics at Cambridge.

5. Jobs/ Career Continued • After that he became: • Chairman of the Advisory Council • Department of Scientific and Industrial Research • Director of the Royal Society Mond Laboratory at Cambridge • A professor of Natural Philosophy at Royal Institution, London

6. The Gold Foil Experiment • Rutherford did this experiment in 1910 • He did it in order to: • Learn more about the structure of an atom • Confirm J.J. Thomson’s “plum pudding” model of an atom:

7. What He Accepted • Rutherford accepted that electrons were present in atoms and that they were negatively charged • He also accepted that there was something inside an atom that made it have a neutral charge and accepted the plum pudding model that had positively charged matter throughout

8. The Experiment • It was set up with a thick lead box with a small opening surrounding a source of heavy, alpha particles • A small beam of the particles was formed pointing at an extremely thin piece of gold foil (approximately 3.4x10-14m thick)

9. The Experiment Continued • He used a fluorescent rotatable detector which has a microscope and a screen coated with zinc sulphide to detect the alpha particles which he wrapped in a circle around the gold foil • The entire experiment was performed in an evacuated chamber in order to prevent scattering by the air molecules • Rutherford expected that all of the particles would go through the foil without any deflection

10. Results • When he performed the experiment, he received some interesting results • When the particles hit the foil, most went straight through, but some of the particles were deflected off at angles and even a few bounced right back off of the foil.

11. Conclusions • Since most of the particles went straight through, he concluded that most of the space in an atom is empty • Since some of the particles deflected or bounced straight back, he concluded that there must be a concentrated area that is positively charged • Also since only a very small amount of the particles were deflected, he concluded that the area of the positively charged particles must be very small

12. “Nucleus of an atom” • http://www.youtube.com/watch?v=Q8RuO2ekNGw

13. Rutherford’s Atomic Model • Was also known as the “planetary model” • It had 2 changes compared to the plum pudding model: • A high concentrated area of positively charges particles is central and very small compared to the rest of the atom (later named the nucleus) • The nucleus contains most of the atomic mass of the atom • Rutherford was the first to discover and prove the existence of positive central charge

14. Rutherford’s Atomic Theory • Most of the space in an atom is empty • Almost all the mass of an atom is concentrated in the center of the atom • In the center of the atom there are positively charged particles • The negatively charged particles revolve around the nucleus in different orbits • The center region of the nucleus is extremely small

15. Sources • http://www.rutherford.org.nz/biography.htm • http://www.nobelprize.org/nobel_prizes/chemistry/laureates/1908/rutherford-bio.html • http://physics.tutorvista.com/modern-physics/rutherford-s-gold-foil-experiment.html