Rutherford Scatter Experiment In an early model, the atom was imagined as a sphe
ID: 1884254 • Letter: R
Question
Rutherford Scatter Experiment
In an early model, the atom was imagined as a sphere of positive charge with negatively charged electrons dotted around inside, rather like plums in a pudding. An experiment was carried out to test the plum pudding model of the atom but the results were unexpected. In 1905 Rutherford designed an experiment to test the plum pudding model. It was carried out by his assistants Geiger and Marsden. A beam of alpha particles was aimed at very thin gold foil and their passage through the foil detected. The scientists expected the alpha particles to pass straight through the foil but something else also happened. Some of the alpha particles emerged from the foil at different angles and some even came straight back. The scientists realized that the positively charged alpha particles were being repelled and deflected by a tiny concentration of positive charge in the atom. In the question below you will calculate how tiny the concentration of positive charge had to be to cause the alpha particle to stop and recoil. As a result of this experiment, the plum pudding model was replaced by the nuclear model of the atom. Rutherford had two assistants Geiger and Marsden. They carried out the following procedure. Radioactive radium emits high velocity and high energy alpha particles. These high energy particles were directed toward a very thin sheet of gold foil. Gold was used because it can be made very thin) without falling apart. Gold atoms contain 79 protons (atomic number 79) and so have a charge of+79 e. Alpha particles consist of two protons and two neutrons having a charge of +2e and a mass of 4 u (atomic mass units) or 6.64 x 10-27 kg. Alpha particles are ejected by the radium at 1.42 x 10 m/s. These particles were directed toward the gold atoms in an ultra-thin gold foil. How close must an alpha particle get to the gold nucleus in order to be stopped and turned around? Since gold atoms are about 50X more massive than alpha particles we assume the gold nucleus remains stationary. Use the Law of Conservation of energy (LCE) to find how close the alpha particle must approach the gold atom to be stopped before reversing direction and rebounding back. You answer should show three significant figures and be given in units of femto-meters or 10A-15 m. Show units of fm. aipha particies gold 7De shield radlooctive goildExplanation / Answer
initial kinetic energy would be converted to electrical potential energy when the alpha particle stops
hence 0.5*mass of alpha particle*initial speed^2=k*charge of nucleus*charge of alpha particle/distance between them
k=coloumb’s constant
==>distance between them=(9*10^9)*(79*1.6*10^(-19))*(2*1.6*10^(-19))/(0.5*6.64*10^(-27)*(1.42*10^7)^2)
=5.4378*10^(-14) m
=54.4*10^(-15) m
=54.4 fm
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.