![]() How a scientific explanation is conditional but may become more convincing when predictions based on the model or theory are confirmed later on by further ideas/scientific data. ![]() The PowerPoint covers how a theory may change as new evidence is found. If the nucleus is larger, the positive charge is larger and the expected deflections are larger-more α particles will be deflected, and the deflection angles will be larger.This extra lesson is not explicitly covered by the Cambridge iGCSE syllabus but it makes a nice addition to the course, as project work, an introduction to the idea of scientific models or just as an introduction to the periodic table or atomic theory.Įach PowerPoint contains a lot of detail, thus this lesson is not really intended to be delivered in the presentation format as like my other lessons. If the nucleus is smaller, the positive charge is smaller and the expected deflections are smaller-both in terms of how closely the α particles pass by the nucleus undeflected and the angle of deflection. Higher-energy α particles that pass near the nucleus will still undergo deflection, but the faster they travel, the less the expected angle of deflection Answer c The more directly toward the nucleus the α particles are headed, the larger the deflection angle will be. ![]() Those α particles that pass near the nucleus will be deflected from their paths due to positive-positive repulsion. The Rutherford atom has a small, positively charged nucleus, so most α particles will pass through empty space far from the nucleus and be undeflected. What generalization can you make regarding the type of atom and effect on the path of α particles? Be clear and specific. Repeat this with larger numbers of protons and neutrons. Does this match your prediction from (c)? If not, explain why the actual path would be that shown in the simulation. Pause or reset, select “40” for both protons and neutrons, “min” for energy, show traces, and fire away. Does this match your prediction from (b)? If not, explain the effect of increased energy on the actual path as shown in the simulation. Pause or reset, set energy to “max,” and start firing α particles. Does this match your prediction from (a)? If not, explain why the actual path would be that shown in the simulation. Due to the scale of the simulation, it is best to start with a small nucleus, so select “20” for both protons and neutrons, “min” for energy, show traces, and then start firing α particles. (d) Now test your predictions from (a), (b), and (c). What factor do you expect to cause this difference in paths, and why? (c) Predict how the paths taken by the α particles will differ if they are fired at Rutherford atoms of elements other than gold. ![]() (b) If α particles of higher energy than those in (a) are fired at Rutherford atoms, predict how their paths will differ from the lower-energy α particle paths. Explain why you expect the α particles to take these paths. (a) Predict the paths taken by α particles that are fired at atoms with a Rutherford atom model structure. Predict and test the behavior of α particles fired at a Rutherford atom model. There was no apparent slowing of the α particles as they passed through the atoms. The α particles followed straight-line paths through the plum pudding atom. Higher-energy α particles will be traveling faster (and perhaps slowed less) and will also follow straight-line paths through the atoms. The plum pudding model indicates that the positive charge is spread uniformly throughout the atom, so we expect the α particles to (perhaps) be slowed somewhat by the positive-positive repulsion, but to follow straight-line paths (i.e., not to be deflected) as they pass through the atoms. Does this match your prediction from (b)? If not, explain the effect of increased energy on the actual paths as shown in the simulation. Hit the pause button, or “Reset All.” Set “Alpha Particles Energy” to “max,” and start firing α particles. Set “Alpha Particles Energy” to “min,” and select “show traces.” Click on the gun to start firing α particles. Select the “Plum Pudding Atom” tab above. (c) Now test your predictions from (a) and (b). (b) If α particles of higher energy than those in (a) are fired at plum pudding atoms, predict how their paths will differ from the lower-energy α particle paths. (a) Predict the paths taken by α particles that are fired at atoms with a Thomson’s plum pudding model structure. ![]() Predict and test the behavior of α particles fired at a “plum pudding” model atom. ![]()
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