explain ruherfords experiment of discovery of nucleus also give its observations and conclusion
Answers
Answer:
Observations of Rutherford's Alpha Scattering Experiment
The observations made by Rutherford led him to conclude that: A major fraction of the α-particles bombarded towards the gold sheet passed through it without any deflection, and hence most of the space in an atom is empty.
Answer and Explanation:
Ernest Rutherford and the gold foil experiment
The next groundbreaking experiment in the history of the atom was performed by Ernest Rutherford, a physicist from New Zealand who spent most of his career in England and Canada. In his famous gold foil experiment, Rutherford fired a thin beam of \alphaαalpha particles (pronounced alpha particles) at a very thin sheet of pure gold. Alpha particles are helium nuclei left parenthesis, and they are given off in various radioactive decay processes. In this case, Rutherford placed a sample of radium (a radioactive metal) inside a lead box with a small pinhole in it. Most of the radiation was absorbed by the lead, but a thin beam of \alphaαalpha particles escaped out of the pinhole in the direction of the gold foil. The gold foil was surrounded by a detector screen that would flash when hit with an \alphaαalpha particle.
Based on Thomson's plum pudding model, Rutherford predicted that most of the \alphaαalpha particles would pass straight through the gold foil. This is because the positive charge in the plum pudding model was assumed to be spread out throughout the entire volume of the atom. Therefore, the electric field from the positively charged "soup" would be too weak to significantly affect the path of the relatively massive and fast-moving \alphaαalpha particles.
The results of the experiment, however, were striking. While almost all of the \alphaαalpha particles passed straight through the gold foil, a few \alphaαalpha particles (about 111 in 202020,000000000) were deflected more than 90° from their path! Rutherford himself described the results with the following analogy: "It was quite the most incredible event that has ever happened to me in my life. It was almost as incredible as if you fired a 15 inch shell at a piece of tissue paper and it came back and hit you."
The nuclear model of the atom
Based on his experimental results, Rutherford made the following conclusions about the structure of the atom:
- The positive charge must be localized over a very tiny volume of the atom, which also contains most of the atom's mass. This explained how a very small fraction of the \alphaαalpha particles were deflected drastically, presumably due to the rare collision with a gold nucleus.
- Since most of the \alphaαalpha particles passed straight through the gold foil, the atom must be made up of mostly empty space!
This led Rutherford to propose the nuclear model, in which an atom consists of a very small, positively charged nucleus surrounded by the negatively charged electrons. Based on the number of \alphaαalpha particles deflected in his experiment, Rutherford calculated that the nucleus took up a tiny fraction of the volume of the atom.
The nuclear model explained Rutherford's experimental results, but it also raised further questions. For example, what were the electrons doing in the atom? How did the electrons keep themselves from collapsing into the nucleus, since opposite charges attract? Luckily, science was ready for the challenge! Physicists such as Niels Bohr continued to design experiments to test the nuclear model of the atom, which eventually evolved into the modern quantum mechanical model.