Instructions In 1909 the picture of the atom was completely different than we know it today. Although electrons had been discovered, neither protons nor neutrons were yet known. Atoms were thought to be like a scoop of chocolate chip cookie dough ice cream, with the chips being the electrons, and the ice-cream having positive charge. Prof Ernest Rutherford set his students, Hans Geiger and Ernest Marsden the task of studying how alpha particles (He nuclei, consisting of 2 protons and 2 neutrons) would be deflected when they were fired at high speed into gold atoms. Gold (79 protons and 118 neutrons) was chosen because it was possible to make it into super-thin sheets, to insure that the alpha particles hit only one gold nucleus, and of course it wouldn't react (iron could oxidize, for example). While they expected to find modest deflections, and mostly did, Geiger and Marsden were astounded to find some alpha particles bouncing almost straight back...an event Rutherford later said was \"as if you had fired a 15-inch [artillery] shell at a piece of tissue paper and it came back and hit you.\" He finally hit upon the only possible explanation he could see, namely that almost all the atom's mass was concentrated in a tiny bit of space. Nuclei of gold have a radius of about 7 x 10'15m. Atoms have radii of about 10'10m. If you made an atom the size of a beach ball, the nucleus would be the size of a blood cell, yet it holds 99.95% of the mass. Multiple This test allows multiple attempts. Attempts Force This test can be saved and resumed later. Completion Vour answers are saved automatically. :5 Question Completion Status: QUESTION 1 20 points Save Answer If they had used protons instead of He nuclei as the probing particles, the force of repulsion of the probe particle at the edge of the gold nucleus would be 0 a. 16 times weaker 0 b4 times weaker O c.2 times weaker O d.the same QUESTION 2 20 points Save Answer If they had used protons instead of He nuclei, the electric field from the nucleus would be a. 16 times weaker O b. 4 times weaker O c.2 times weaker O d. the same QUESTION 3 20 points Save Answer Consider the electric field due to the gold's nucleus, measured at the edge of the atom. If you move to a location where that electric field is doubled, where are you? (A) Half the distance to the nucleus from the atom's edge. (B) 1/4 the distance to the nucleus from the atom's edge (C) 70% of the distance from the atom's center. (D) 70% of the distance from the atom's edge. (E) None of the above. O a. Half the distance to the O b. 1/4 the distance to the O c.70% of the distance O d. 70% of the distance O e. None of nucleus from the atom's nucleus from the atom's from the atom's from the atom's the above edge. edge center. edge QUESTION 4 20 points Save Answer Which diagram best shows the field between the alpha particle and the gold nucleus? O a. a Ob. b O c.c O d.dQUESTION 5 Which of the diagrams (shown in the question above) now best shows the field between a proton and an electron? Oa.a Ob.c O c.c O d.d