(a) Thomson's cathode-ray tube (Figure 2.4) and the mass spectrometer (Figure 2.11) both involve the use of electric or magnetic fields to deflect charged particles. What are the charged particles involved in each of these experiments?

Video transcript

Welcome back everyone in this example, we need to list the charged particles involved in a Thompson's cathode ray tube and then in be our mass spectrometer. So we're going to begin by drawing out our apparatus in part a are Thompson's cathode ray tube. So we'll draw a tube represented by this circle. Were on one end of our tube we have a cathode electrode which we should recall has a negative charge. And then on the other end we have an an ode electrode which we should recall bears a negative charge. Or sorry, a positive charge at the anodes. We also have a screen behind our node which is coated in foss for so this is a fox fur coated screen. And then we also will apply these electric plates to our tube where one plate is going to bear a positive charge and the other plate is going to bear a negative charge. So these are our electric plates. So what happens in this setup is we take a electron beam otherwise known as a cathode ray and that is produced from our cathode and it's going to travel towards our anote electrode where it's going to deflect towards the positively charged electric plate as well as towards our phosphor coated screen. And it's going to produce a bright light on the screen. So I'll just highlight that bright light on all over the screen here in light purple, which because our cathode ray is attracted to our electric plate with the positive charge Thompson was able to make the generalization that our cathode ray is composed of negatively charged particles, which we now understand as electrons. So our cathode ray is now understood as an electron beam recall that electrons have a negative charge. And Thompson was also able to uncover our mass to charge ratio of an electron and he determined that that value is equal to negative 1.76 times 10 to the eighth power columns per gram. So for our first answer, we can confirm that the charged particle involved is going to be the electron. That is for our setup for Thompson's cathode ray tube in part A. So now we will go and highlight our apparatus for part B, which is our mass spectrometer. So what we have here first is a our cathode ray tube. And now we want to draw out Thompson's or sorry, the mass spectrometer. So this is for part B. So we're going to scroll below for more room to draw out our apparatus here. So we have first a inlet that we're going to draw where our sample enters the apparatus. And then we have this region of our mass spectrometer which extends into a tube that ultimately leads to this detector here below. So this is going to be a detector. Sorry about that. So this is our detector. We also have surrounding our tube, a set of two magnets which produce a magnetic field that's going to go through the tube. So these are our magnets and then in this region we have a electric beam source as well as in this region we have accelerator plates and on one side we have a negative charge on the other side of our accelerator plate we have a positive charge. And then again this is our sample inlet. So what happens with our mass spectrometer is we have a sample of any element that becomes atomized. So we'll draw our sample by this pink circle and it's atomized by electrons. It's bombarded by all these electrons that atomize our sample and when our sample is heated and atomized it's going to lose electrons. So these electrons are going to be removed. Which then produces our sample as a positively charged ion. And so these positively charged ions are going to be traveling through our spectrometer and then they're going to go through our magnetic field. So sorry, these are all positively charged, where some will be deflected and those will be the ions that are of low mass. Whereas the ions that are of a higher mask are going to be analyzed by our detector here at different detection points where these ions are analyzed for their abundance in nature. And this is how we are able to understand different isotopes of various elements. And we can use the information from our detector in our mass spectrometer to create a chart which plots the mass to charge ratio of our abundance of these isotopes. And so as we stated in our mass spectrometer we have these positively charged ions that are produced. So we want to recall that these positively charged ions are known as cat ions and these are the charged particles involved in our mass spectrometer setup. So this would be our second and final answer for part B. So everything highlighted in yellow represents the two types of charged particles involved in first the Thompson's cathode ray tube, which was the electron, and then in part B, the mass spectrometer, we have the charged particle being involved as a caddy on. So I hope that everything I explained was clear. If you have any questions, leave them down below and I will see everyone in the next practice video.