Causes of ionization

[mms2k7]

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Ok, so i thought i understood this, but obviously i didnt.

An ionized particle is simply a charged particle right? you can be + (cation) or - (anion).

Several ways to end up with ionization, most commonly you do it by ejecting an electron(s) out, and the particle ends up with a net+ charge.

So.. in order to ionize, say, an atom, i can hit it with a photon that has enough KE to eject an e-, k cool

I can have another electron knock out an electron on a different atom (provided there is enough E)

BUT can ionization ONLY occur using charged particles??

I took this aamc practice test.. and one of the explanations was basically to the effect of neutrons cannot cause ionization in other particles because they are not charged...

What if you accelerated neutrons through a proportional chamber, wouldnt they eventually collide with other particles in the chamber, and cause ionization by knocking out e-??

 

[georgia_md]

Ok, so i thought i understood this, but obviously i didnt.

An ionized particle is simply a charged particle right? you can be + (cation) or - (anion).

Several ways to end up with ionization, most commonly you do it by ejecting an electron(s) out, and the particle ends up with a net+ charge.

So.. in order to ionize, say, an atom, i can hit it with a photon that has enough KE to eject an e-, k cool

I can have another electron knock out an electron on a different atom (provided there is enough E)

BUT can ionization ONLY occur using charged particles??

I took this aamc practice test.. and one of the explanations was basically to the effect of neutrons cannot cause ionization in other particles because they are not charged...

What if you accelerated neutrons through a proportional chamber, wouldnt they eventually collide with other particles in the chamber, and cause ionization by knocking out e-??

No. Neutrons don't interact strongly with electrons so they are not involved directly with ionization. Most interactions will be nuclear, meaning in the nucleus. Wow, I am shocked, AAMC appears to be correct

 

[mrmilad]

Another way to look at this explanation of the necessity for a charged particle is to look at the electrostatic interaction when two particles collide to cause ionization. The kenetic energy required for ionization is the energy required to overcome the Zeffective on the electron, but I see only charged particles interacting with electrons at a distance. Only then will there be a electrostatic repulsion or attraction between the two colliding particles. The repulsive force of an electron against the electron of the atom would exponentially increase as their distance decreases to the point where when they are touching it is maximized and the electron overcomes the Zeff. Furthermore if you think of electrons as so small that only their charge would effectively cause long range interactions (aka electrostatic) then a Neutron would only cause ionization during a direct impact with the proper KE. Conceptually I tend to think as Neutrons as so much more massive than electrons than it would be impossible to hit one electron alone by a single neutron. That is my 2 cents, if it helps at all.😱

 

[georgia_md]

Another way to look at this explanation of the necessity for a charged particle is to look at the electrostatic interaction when two particles collide to cause ionization. The kenetic energy required for ionization is the energy required to overcome the Zeffective on the electron, but I see only charged particles interacting with electrons at a distance. Only then will there be a electrostatic repulsion or attraction between the two colliding particles. The repulsive force of an electron against the electron of the atom would exponentially increase as their distance decreases to the point where when they are touching it is maximized and the electron overcomes the Zeff. Furthermore if you think of electrons as so small that only their charge would effectively cause long range interactions (aka electrostatic) then a Neutron would only cause ionization during a direct impact with the proper KE. Conceptually I tend to think as Neutrons as so much more massive than electrons than it would be impossible to hit one electron alone by a single neutron. That is my 2 cents, if it helps at all.😱

I think Zeff is the measure of of electrostatic interaction between negatively charged electrons and positively charged protons. Not between electron and electron. Electrons won't touch because my physics professor told us that like charges repel each other.

 

[mrmilad]

Zeff is the effective charge felt by the electron from the nucleus(positive), thus it is the attractive force that is keeping the electron connected to the atom. That is what I was referring to, the electron collision must over come that attractive force that is cause by the Zeff on the electron in order to cause it to get bumped away. And yes electrons do repel eachother that is why when a "collision occurs" it is actually a repulsive force that you can find by using columbs law F= kq1q2/r^2 where q1 and q2 both have the same charge. As the distance between the two charged decreases, the Force increases by the square, thus when they are almost touching there is a huge repulsive force causing one to get bumped.

 

[mms2k7]

Zeff is the net force felt on an electron from the positive charge of the nucleus. Zeff for an e- is generally much smaller than the calculated Z because of shielding from other shells. Hence the periodic trends for radius.

Anyways, i know neutrons DONT interact with electrons, since they arent even free orbiting. I was simply talking about neutron bombardment, and wondering if it was capable of causing ionization.
mrmilad--ya i conceptualized it like you did, i figure a neutron is SO big compared to an e- itd be impossible for it to hit just an electron to ionize it; and yep, the repulsive force has a great deal of potential energy, hence the classic bond graph of two atoms being brought together from infinity.

 

[georgia_md]

Zeff is the net force felt on an electron from the positive charge of the nucleus. Zeff for an e- is generally much smaller than the calculated Z because of shielding from other shells. Hence the periodic trends for radius.

Anyways, i know neutrons DONT interact with electrons, since they arent even free orbiting. I was simply talking about neutron bombardment, and wondering if it was capable of causing ionization.
mrmilad--ya i conceptualized it like you did, i figure a neutron is SO big compared to an e- itd be impossible for it to hit just an electron to ionize it; and yep, the repulsive force has a great deal of potential energy, hence the classic bond graph of two atoms being brougt together from infinity.

you shoot a free neutron at an atom, it's most likely to hit particles of similiar size; proton.

 

[georgia_md]

Zeff is the effective charge felt by the electron from the nucleus(positive), thus it is the attractive force that is keeping the electron connected to the atom. That is what I was referring to, the electron collision must over come that attractive force that is cause by the Zeff on the electron in order to cause it to get bumped away. And yes electrons do repel eachother that is why when a "collision occurs" it is actually a repulsive force that you can find by using columbs law F= kq1q2/r^2 where q1 and q2 both have the same charge. As the distance between the two charged decreases, the Force increases by the square, thus when they are almost touching there is a huge repulsive force causing one to get bumped.

Wow, where did you go to school? haha, there won't be any repulsive force. If q1q2 is negative, force will be attractive. Anyways, I think if they touch, then distance would be zero. That's undefined

 

[mrmilad]

Wow, where did you go to school? haha, there won't be any repulsive force. If q1q2 is negative, force will be attractive. Anyways, I think if they touch, then distance would be zero. That's undefined

Please reread what I said and do some math. Regarding the distance, if you have taken precalculus or any calculus you will know that the term
1/n = infinity as n approaches zero which describes the nature (Magnitude) of the repulsive force between the two electrons. As I said "a repulsive force that you can find by using columbs law F= kq1q2/r^2 where q1 and q2 both have the same charge". When q1 and q2 are both negative(2 electrons), then the force will be repulsive; likewise if both are positive the force will again be repulsive. Only when q1 and q2 have opposite signs ie. proton and electron, will there be attractive force between the two.

 

[georgia_md]

Please reread what I said and do some math. Regarding the distance, if you have taken precalculus or any calculus you will know that the term
1/n = infinity as n approaches zero which describes the nature (Magnitude) of the repulsive force between the two electrons. As I said "a repulsive force that you can find by using columbs law F= kq1q2/r^2 where q1 and q2 both have the same charge". When q1 and q2 are both negative(2 electrons), then the force will be repulsive; likewise if both are positive the force will again be repulsive. Only when q1 and q2 have opposite signs ie. proton and electron, will there be attractive force between the two.

I got a B in calculus II and an A in physics II, years ago. But you're right, when you said two particles were equal in charge, I was thinking |q1|x|q2| where the product is positve. It's been a while since I looked at coloumb's law. Anyways, electrons can never actually "hit"