Atomic Theory

Prepared By : Aditya Kumar Pathak

Rutherford

Index1. About Rutherford2. Rutherford model3. Rutherford gold foil experiment4. Rutherford gold foil experiment result5.

Rutherford gold foil experiment conclusion

6. Rutherford’s Model of the Atom: Planetary Model (w/o orbits)

7. The Nucleus8. Video related to gold foil experiment9. History of Atom

About Rutherford Ernest Rutherford,

1st Baron Rutherford of Nelson  (30 August 1871 – 19 October 1937) was a New Zealand-born British chemist and physicist who became known as the father of nuclear physics. He is considered the greatest experimentalist since Michael Faraday (1791–1867).In early work he discovered the concept of radioactive half-life, proved that radioactivity involved the transmutation of one chemical element to another, and also differentiated and named alpha and beta radiation. This work was done at McGill University in Canada. It is the basis for the Nobel Prize in Chemistry he was awarded in 1908 "for his investigations into the disintegration of the elements, and the chemistry of radioactive substances“.

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Rutherford model

The Rutherford model is a model of the atom devised by Ernest Rutherford. Rutherford directed the famous Geiger-Marsden experiment in 1909 which suggested, upon Rutherford's 1911 analysis, that the so-called "plum pudding model" of J. J. Thomson of the atom was incorrect. Rutherford's new model for the atom, based on the experimental results, contained the new features of a relatively high central charge concentrated into a very small volume in comparison to the rest of the atom and with this central volume also containing the bulk of the atomic mass of the atom. This region would be named the "nucleus" of the atom in later years.

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Rutherford Gold Foil Experiment

1) A narrow beam of alpha particles was aimed at a thin sheet of gold foil

2) A zinc sulfide-coated screen surrounding the gold foil produced a flash of light when struck by an alpha particle (radioactive materials expose photographic film)3) By noting where the flashes occurred,

the scientists could determine if the atoms in the gold foil deflected the alpha particles Index

Rutherford Gold Foil Result

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Rutherford’s Results & Conclusions

Most of the particles went straight through the gold foil Conclusion: The atom is made up of mostly empty space

Several particles were deflected straight back toward the source! Conclusion: There is a massive, densely packed area within an atom

(this is the discovery of the nucleus) Rutherford likened this surprising result to firing a large artillery shell

at a sheet of paper and the shell coming back at the cannon!A few particles were deflected at large angles.

Conclusion: The nucleus must be positive because the positive alpha particles are being deflected from a positive center (like charges repel).

NOTE: Neutrons were not discovered until 1932! Rutherford discovered the nucleus – not protons and neutrons!

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Rutherford’s Model of the Atom: Planetary Model (w/o orbits)

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The Nucleus

• In 1911, Ernest Rutherford (1871-1937) began to study how positively charged alpha particles (radioactive helium nuclei) interacted with solid matter.

• With a small group of scientists (most notably, Hans Geiger, of the Geiger Counter fame), Rutherford conducted an experiment to see if alpha particles would be deflected as they passed through a thin gold foil (like aluminum foil).

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Rutherford’s new evidence allowed him to propose a

more detailed model with a central nucleus.

He suggested that the positive charge was all in a

central nucleus. With this holding the electrons in place

by electrical attraction

However, this was not the end of the story.

History of the Atom

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Thank You

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