1 / 19

Atomic Theory

Part 2: Rutherford and the Gold Foil Experiment. Atomic Theory. The Story So Far…. The Discovery of the Nucleus. Ernest Rutherford was a student under J.J. Thomson. Moved to Montreal to study at McGill!. Holla - Canada!. Rutherford’s Work.

lise
Download Presentation

Atomic Theory

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Part 2: Rutherford and the Gold Foil Experiment Atomic Theory

  2. The Story So Far…

  3. The Discovery of the Nucleus • Ernest Rutherford was a student under J.J. Thomson Moved to Montreal to study at McGill! Holla- Canada!

  4. Rutherford’s Work • Radioactive elements were just recently understood • They give off rays of energy as they break down • These rays are known as “radioactive decay”

  5. Rutherford’s Work • Rutherford studied alpha particles • Emitted from decaying radioactive elements (ex. Radium, Polonium) • Alpha particles are large and have a positive charge

  6. Rutherford’s Work • To further study the atom, he decided to fire alpha particles at a thin sheet of gold • He expected the particles being shot at the gold would pass through in a straight line

  7. Rutherford’s Work • But he was surprised! • Most of the particles went straight through • Some were deflected off course (weird) • Some bounced right back at him (weirder!) • How in the world would he explain this??

  8. Gold foil atoms

  9. Rutherford’s Work • Since alpha particles are positive and they bounced right back at him… • Rutherford proposed that a small area of positive charge existed in the atom • The alpha particles were repelled by the like-charged centre of the gold atoms

  10. Rutherford’s Work (+) (+) (+) (+) (+) (+)

  11. Rutherford’s Work • Rutherford named the centre of the atom “nucleus” • Proposed the nucleus had a positive charge • Proposed electrons orbited the nucleus, like planets around the Sun

  12. Rutherford’s Work • Rutherford’s observations can be summarized as follows:

  13. Thomson’s model vs Rutherford’s model Major advancement in the understanding of the atom!

  14. The next find… • A Danish scientist (Neils Bohr) traveled to England to work with now-famous Rutherford Famous Curious

  15. Bohr’s Contribution • Bohr figured Rutherford was mostlycorrect… • He passed electricity through hydrogen gas and bands of light appeared • Light bands corresponded with quantity of energy applied to the gas • Unique bands of light were given off by ALL elements

  16. Bohr’s Contribution • Bohr reasoned that electrons moved in fixed regions or energy levels • For an electron to move up a level, it needed outside energy to “bump it up” • The amount of energy required to excite an electron was called a “quantum” • The discipline of quantum mechanics was born!

  17. Where can electrons be found? In concentric “shells” around the nucleus… … but in 3 dimensions

  18. Bohr-Rutherford Model of the Atom • Think of a person on a ladder: • You can’t stand between the rungs!

  19. Bohr-Rutherford Model of the Atom • Electrons can be “bumped up” after absorbing energy or they can “fall down” if energy is not sustained

More Related