Rutherford Gold Foil Experiment

In 1911, Ernest Rutherford's gold foil experiment led to the discovery of the positively charged nucleus within an atom. Now he was assisted by fellow chemists hans Geiger and Ernest Marsden and because they had such a big role in this experiment, it's sometimes also referred to as the Geiger Marsden experiment. Okay, so just remember that this experiment is given by both of these names. The Rutherford Gold experiment, as well as the Geiger Marsden experiment. Now the experimental setup is a thin sheet of gold foil. So here we have our gold foil right here is bombarded with alpha particles emitting emitting from a radioactive element. Now the alpha particle itself, It's a radioactive particle consisting of two protons and two neutrons. So if we were to write out its elemental symbol. Alright, so we're going to say it has two protons, which means that the atomic number is two. Its mass number is a number of neutrons and protons together. That'd be a total of four. And would use the alpha symbol here. We're not talking about any electrons involved, neutrons are neutral, protons are positive. So the overall charge will be two. Plus. Now we'd say that an element on the periodic table also has an atomic number of two and that would be helium. So another way of depicting this alpha particle is 4/2 helium two Plus. Now we're going to say here that the radioactive element is encased within this lead box with one part of it open, which emits the awful particles. Now the radioactive element itself is usually Iridium and again, it's in case within this lead container. Now we're going to say here that around this gold foil or gold sheet, we're going to have what's called our detecting screen. So which is this screen right here and it has a small slip which allows for the passage of the alpha particles to enter. Now, what happens here is that the alpha particles are emitted from the iridium. And what we saw is that some of the alpha particles would go through the gold foil and they would hit the back of the detecting screen. But we also found that some of these positively charged off of particles would be striking something in the center of our gold foil. This would cause some of these alpha particles to change trajectories. They wouldn't go straight through it. They would hit different parts of the detecting sheet would surprise our chemists and in some cases the alpha particle would shoot out towards the gold foil and come right back towards the radioactive source. Now from this, we were able to come up with, well, Rutherford was able to come up with his three postures and the apostle, it's were one that the proton and neutron are located in the nucleus which lies at the center of the atom. And Rutherford was also able to determine that although incredibly small, the nucleus comprised most of the mask of the And then finally Rutherford was able to figure out that surrounding the dense poverty charged nucleus is a cloud of electrons. So from the gold foil experiment were able to come up with these three postulates, in the case of Rutherford and his assistants. Now these are seen as common known ideas today, but back then it was pretty groundbreaking and went against a lot of, at the time laws at least people chemists consider them to be lost. So this kind of turned all that on top of its head and kind of challenge a lot of the conceptions that chemists had at that time. Okay, so through the actions of Rutherford and Geiger and Marsden, we have a better understanding of the atom.

in this example question. It says the gold foil Rutherford used in his experiment had a thickness of approximately 6.0 times 10 to the minus three millimeters. If a single gold Adam has a diameter of 2.9 times 10 to the negative eight centimeters. How Maney Adams thick was Rutherford's foiled. All right, so here we need to determine what is our end amount here. They want us to determine the amount of atoms so the number of atoms will be our end amount and are given amount is just the value that possesses only one unit connected to it. Within this question, we have to values being given here. They're saying that we have 6.0 times 10 to the minus three millimeters, and in this other value, it's actually not alone. It's actually a conversion factor. It's telling us one Adam has this value. So the conversion factor is one. Adam is 2.9 times 10 to the negative eight centimeters. Remember, we're gonna start with are given amount, which is just a value alone that is not connected. Toa another unit. So we have 6.0 times 10 to the minus three millimeters. That is our given amount. Remember, we use conversion factors to go from, are given amount, tow our end amount and realize here that if I can convert these millimeters into centimeters, they can cancel out with these centimeters. And in that way we can isolate Adams at the end. So that is the approach we're going to take. So our first conversion factor is just going to be converting millimeters to meters. Remember, the coefficient of one goes on the side with the metric prefix meaning one Millie is 10 to the negative. Three millimeters can't slop Now I have meters for conversion factor to now I'm gonna go from meters, two centimeters. One senti is 10 to the negative too. Now that I have centimeters, I can now bring in my conversion factor from the question itself which is conversion factor three So 2.9 times 10 to the negative. Eight centimeters per one. Adam. So here centimeters cancel out and I'll have Adams at the end. Make sure you put this in parentheses in your calculator. Otherwise you make a thing incorrect. Answer. And remember, we do that every time. We have times 10 20 power if you that correctly, you'll get as your final answer to one times 10 to the four acts, so we would have 2.1 times 10 to the four atoms in terms of another atoms involved in the thickness of Rutherford's foil.

now, through the use of the rough for gold foil experiment, were able to develop a new model for the Adam itself. We coin it, the nuclear model. Now, before Rutherford nuclear model, we had Thompson's plum pudding model. Now with the plum pudding model, it was believed that the atom itself had dispersed around it electrons. So these negatively charged electrons were dispersed evenly throughout the atom. Now, to counterbalance these electrons, we actually had positive charges embedded within the atom. This overall gave the atom a neutral charge. Now, if this were true when Rutherford used his alpha particles, they should have all shot through the app. However, we saw that some of the Alfa particles were being deflected from something near the center of the Adam itself. This helped to create the nuclear model. So with the nuclear model and the ejection off alpha particles from our lead container towards the atom, we saw that some bees alpha particles were deflecting back as we fired alpha particles towards them. Now, of course, some of them did go through because they wouldn't interact with the nucleus itself, but just realized because of the gold foil experiment, Rutherford was able to put to rest this plum pudding model first theorized by Thompson and give us this more accurate nuclear mom.

In this example, It says Rutherford's experiment, which Alba particle scattering by gold foil, established that a electrons are positively charged subatomic particles. Even if we didn't know anything about Rutherford's experiment, we should know that this statement is false. Electrons are not positively charged subatomic particles there negatively charged subatomic particles. Besides, it didn't prove this. It just proved that at the center of the atom rested a positively charged portion. And we know that portion is the nucleus. Next, Adams are composed of protons, neutrons and electrons. Now, yes, the atom is composed of these subatomic particles. Yes, electrons do orbit the nucleus. Rutherford knew that the new place itself were positive. But he wouldn't have known that there were neutrons embedded in it as well. Because, remember, neutrons possessed no charge. There'd be no way of him knowing that they existed within the nucleus as well. So this is not true. Protons are not evenly distributed throughout an Adam. Now here, this is true. Protons are not distributed evenly throughout an atom like Thompson's plum pudding model would have suggested the gold foil experiment proved that at the center of the atom itself is where we have a concentration of those protons, so this would be the most accurate. Finally, protons are about 1000 times lighter than electrons. This is also true. We know that the subatomic particles neutrons are the heaviest, followed by protons and electrons would be the lightest. Also, if the center war highly dense as we believe, we expect the protons to be much more heavy than the electrons themselves. So here, on Lee options see would be the correct choice.