CHADWICK'S EXPERIMENT
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One chilly February day in 1932, James Chadwick discovered that there was more to the nucleus of an atom than just a mass of positively charged matter. What did he find? Read on and see!
EXCLUSIVE INTERVIEW WITH JAMES CHADWICK!
Will: I appreciate you having the patience to deal with me, Mr. Chadwick. Thank your for your time.
Chadwick: Well, all I can say is that it's good to finally knows his position in society.
W: Mr. Chadwick, would you say that this is the definitive version of the atomic model, or will there be found more than three subatomic particles in the future?
C: Oh, yes. I took down Rutherford's model, and there will likely be a more mentally fit man to tackle mine. These theories are always so short lived. You see, we're discovering so much in such a short time.
W: And what is this new particle that you've discovered?
C: Like Rutherford before me, I have opted to call it the neutron. However, not only is Ernest a pain to work with, but he also got neutrons all wrong. As far as we know, neutrons are fundamental particles. They are not made of protons and neutrons. That's foolish. Quantum mechanics as we know it forbids electrons from getting that close to protons.
Chadwick: Well, all I can say is that it's good to finally knows his position in society.
W: Mr. Chadwick, would you say that this is the definitive version of the atomic model, or will there be found more than three subatomic particles in the future?
C: Oh, yes. I took down Rutherford's model, and there will likely be a more mentally fit man to tackle mine. These theories are always so short lived. You see, we're discovering so much in such a short time.
W: And what is this new particle that you've discovered?
C: Like Rutherford before me, I have opted to call it the neutron. However, not only is Ernest a pain to work with, but he also got neutrons all wrong. As far as we know, neutrons are fundamental particles. They are not made of protons and neutrons. That's foolish. Quantum mechanics as we know it forbids electrons from getting that close to protons.
The Experiment
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W: How in the world did you set up something like this experiment? Experimenting on a subatomic level sounds pretty painstaking.
C: Oh, you have no idea. Well, I took a radioactive sample of polonium, which releases alpha particles, and fired those particles at a sheet of beryllium.
W: And what are alpha particles?
C: Good lord! Can't the press send me just at least one chemist who doesn't need everything explained to him as if he's a yellow labrador? An alpha particle contains two protons and, though I didn't know at the time, two neutrons. When I shot this at the beryllium, it bonded with its nucleus, creating Carbon and one neutron.
W: How did you know that this was a neutron and not a proton?
C: I had the neutrons pass through a sheet of wax and to a proton detector in an ionization chamber. If they passed through the nucleus of the paraffin, they would knock a proton loose from its nucleus, like a pool ball transferring its energy to another. However, some didn't pass through the nucleus, and just kept flying towards the proton detector. When one of the loose protons hit the detector, it would acknowledge a positive electrical charge. However, it didn't register any electrical charge from the neutrons. That's how I knew they were different.
W: What's paraffin?
C: Wax. That stuff that wraps your candles and coats your paper that you carry your pitiful, common little pizza slices in when you walk home from your day job at the convenience store.
C: Oh, you have no idea. Well, I took a radioactive sample of polonium, which releases alpha particles, and fired those particles at a sheet of beryllium.
W: And what are alpha particles?
C: Good lord! Can't the press send me just at least one chemist who doesn't need everything explained to him as if he's a yellow labrador? An alpha particle contains two protons and, though I didn't know at the time, two neutrons. When I shot this at the beryllium, it bonded with its nucleus, creating Carbon and one neutron.
W: How did you know that this was a neutron and not a proton?
C: I had the neutrons pass through a sheet of wax and to a proton detector in an ionization chamber. If they passed through the nucleus of the paraffin, they would knock a proton loose from its nucleus, like a pool ball transferring its energy to another. However, some didn't pass through the nucleus, and just kept flying towards the proton detector. When one of the loose protons hit the detector, it would acknowledge a positive electrical charge. However, it didn't register any electrical charge from the neutrons. That's how I knew they were different.
W: What's paraffin?
C: Wax. That stuff that wraps your candles and coats your paper that you carry your pitiful, common little pizza slices in when you walk home from your day job at the convenience store.
Chadwick's Atomic Model
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W: What's this picture, Mr. Chadwick?
C: Wipe that excited smile off your face. Fun is a waste of time. That is my atomic model, more accurate than that of Rutherford. As you can see here, there are two different types of particles in the nucleus: protons and neutrons. The electrons are there as well, in the same vein as Rutherford's model. Good day.
W: Wait! Mr. Chadwick!
C: I have better things to do than speak troll with some high-school educated nose-blow.
W: Of course you do, Mr. Chadwick.
C: Wipe that excited smile off your face. Fun is a waste of time. That is my atomic model, more accurate than that of Rutherford. As you can see here, there are two different types of particles in the nucleus: protons and neutrons. The electrons are there as well, in the same vein as Rutherford's model. Good day.
W: Wait! Mr. Chadwick!
C: I have better things to do than speak troll with some high-school educated nose-blow.
W: Of course you do, Mr. Chadwick.