Which of the subatomic particles in an atom does not have a charge (and was therefore the last to be discovered)?

Video transcript

Everyone in this example, we need to determine which of the following subatomic particles. Either electrons, protons or neutrons was the most difficult to discover and why? So starting off in the year 1897 we wanted to call the experiment known as the cathode very experiment. So in this experiment we have two electrodes, one being our negative electrode here. So it has a negative charge. And then we have another electrode. In this experiment that was used with a positive charge and a high voltage was applied to both of our electrodes. Where these voters, known as cathode rays were produced and how they traveled was from our negative electrode towards our positive electrode. So these are our categories that were produced from the voltage between our electrodes. And because these cathode rays traveled from the negative electrode to the positive electrode. This experiment concluded that therefore cathode rays are negatively charged particles now called electrons and that's how the charge of the electrons were discovered. So this experiment was fairly or proved that electrons aren't so difficult to discover since they were determined to have a negative charge. And now we're going to recall our next experiment which we would recall happened in 1919 known as our rutherford gold experiment. So in this experiment we have the following setup where we have a alpha particle source which fired alpha rays at a piece of gold foil. So this would be our gold foiled here. These are our alpha particles firing through at different angles in the experiment and most of them went through the gold foil. However, some of our alpha particles were not able to penetrate through the gold foil and were deflected at various angles. And because of these deflected alpha particles that occurred in the experiment, this proved that we have a repulsion between the nucleus here of our gold atom. So what I've circled would be representative of our nucleus recall that our nucleus of our atom is surrounded by electrons. So we're just going to draw those around the nucleus. Mm And again as above, we stated that electrons are negatively charged. So because of that deflected alpha particle here in our experiment, we were able to determine a repulsion between the alpha particle and the nucleus of our gold atom or the gold foiled in this case. So what what we should also recognize is that alpha particles are positively charged. So we can conclude that positive alpha particles deflected from the foil proved repulsion between alpha particles and gold's nucleus. So we used the chemical symbol for gold here, which showed that Adams mostly empty space, which is why we had some of the alpha particles passed through the gold foil as shown in the diagram. But the deflected after particles showed that these atoms are mostly empty space with densely packed protons in the nucleus. And so I'm sorry, nucleus spelled as follows. And so therefore the positive charge of protons were discovered. So this experiment was able to conduct the discovery of positively charged protons. So we would say that discovering protons wasn't as difficult as compared to our last experiment, which we're going to recall is going to be a 1932 experiment which happened Or sorry, it happened in 1932. And the experiment was called the Chadwick neutron experiment. So given by the name, you can tell that this experiment proved the discovery of neutrons. And what this setup looked like for this experiment was we had another alpha particle source but in this case it was a radioactive offer particle source which gave off radioactive waves of our alpha particles towards an atom of beryllium which showed no electrical repulsion to these alpha particles. And because of the lack of repulsion, there was a high amount of penetration of that radiation through this atom of beryllium. So the only way the success of this penetration was proved in this experiment was through another part of the setup where we have a piece of paraffin wax which as a result of the high penetration of that radiation from the alpha particles fired at the beryllium atom gave off or dislodged, positively charged protons. And so these positively charged protons being dislodged from the wax proved that the lack of charge given off from the radiation passing through our beryllium atom at a high rate was due to an uncharged force which we determined would be considered as neutrons. So neutrons are went passed through the beryllium atom caused by the high penetration of the radiation from the alpha particles. So from this experiment we can conclude that third floor neutron detector was created when uncharged neutrons dislodged positive charged protons from wax. And so overall the Chadwick neutron experiment mhm proved that the most difficult subatomic particle discovered was the neutron due to its uncharged nature. Oh and this is going to complete this example. This part of our explanation here is going to complete this example as our final answer for this question, which is asking us what was the most difficult subatomic particle to discover. We can agree that it was definitely neutrons because the Chadwick neutron experiment showed that neutrons have no electrical charge, they're neutral. And so this is our final answer. So I hope that everything I explained was clear. If you have any questions, please leave them down below and I will see everyone in the next practice video.