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Home , Rutherford model, Rutherford scattering

Rutherford Experiment Topic covered Quantum Mechanics

Atomic Nuclei Atomic Structure

Alpha Particles

Electric Charges

Electric Force

Rutherford Scattering

Plum Pudding Model

Description How did Rutherford figure out the structure of the without being able to see it? Simulate the famous experiment in which he disproved the of the atom by observing alpha particles bouncing off atoms and determining that they must have a small core. Objectives The following can be learned from this simulation: Identify the qualitative difference between scattering off positively charged nucleus and electrically neutral plum pudding atom. Intrepretqualitatively for charged nucleus, how angle of deflection depends on: Energy of incoming particle, Impact parameter, Charge of target. Instructions Here you can see two tabs, Rutherford atom and Plum pudding atom. The first tab is Rutherford atom. On the right side of the screen, set the energy of properties value between MIN and MAX. Also, Show Traces box should be checked off. Now, turn on the gun by clicking on it and observe what happens when the alpha particles are fired at the atom’s nucleus. Next, move on to the Plum pudding atom tab. Keep the energy as same as before and keep Show traces checked. Turn on the gun again by clicking on it, observe what happens for a few minutes. Now, play around with both models and adjust the various settings and notice the changes if any.

Observations

What atom is being represented in ?

What is happening to the majority of the alpha particles in Rutherford’s model?

What did Rutherford prove about the atom from this experiment?

E How is this result of Plum pudding model different from the result shown with Rutherford’s r Nuclear model? n e s t

R Eu Which model is closer to the version of today’s modern model of the atom? Why? rt nh e sr tf o Rr ud t h( e1 r8 f7 o1 r- d1

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Quiz

Which of the following scientists developed the "plum-pudding" model of the atom? John J. J. Thomson Henry Moseley In Rutherford's experiment, a thin foil was bombarded with alpha particles. According to Thomson's "plum-pudding" model of the atom, what should have happened? All the alpha particles would have been deflected by the foil. All the alpha particles should have bounced straight back from the foil. Alpha particles should have passed through the foil with little or no deflection. Alpha particles should have become embedded in the foil. Rutherford's alpha particle scattering experiment established that: protons are not evenly distributed throughout an atom. have a negative charge. electrons have a positive charge. atoms are made of protons, , and electrons. protons are 1840 times heavier than electrons. Which of the following scientists developed the nuclear model of the atom? J. J. Thomson Henry Moseley Ernest Rutherford Rutherford’s α–particle scattering experiment showed that I. electrons have negative charge II. the and positive charge of the atom is concentrated in the nucleus III. exists in the nucleus IV. Most of the space in atom is empty. Which of the above statements are correct? (i) and (iii) (ii) and (iv) (i) and (iv) (iii) and (iv)

Reference

Ernest Rutherford (1871-1937) English physicist born in Nelson, New Zealand. In 1906, his students Geiger and Marsden conducted the classic gold foil alpha particle scattering experiment which showed large deflections for a small fraction of incident particles. This led Rutherford to propose that the atom was "nuclear." For his discoveries, Rutherford was awarded the 1908 Nobel Prize in chemistry. Rutherford suggested the fundamental positively charged particle, which he called the proton in 1914.

Sources and References

http://www4.uwsp.edu/chemistry/tzamis/ch115pdfs/atomicstructscientists.pdf