Physics help? ionisation lol?

[jewii]

got my A2 exams coming up soon and i was hoping if someone could tell me what ionisation is in GCSE level, yeah i only started learning in AS so everything in GCSE is a blur.

i understand how it describes the effect of an atom loosing an electron from numerous factors, i.e. alpha,gamma and beta. does anything special happen to the atom than becoming negatively charged?

From AS i remember if we fired electrons towards atoms, some electrons took out other electrons which were apart of a atom causing the atom excite and release energy in photon form. i think thats right.

and i guess alpha simply pulls electronics from the atom with being +2 in charge.

and what i've researched on gamma, it randomly does pair production when in a atom???

 

[Vonhelmet]

Alpha emission: the nucleus emits two protons and two neutrons, effectively a helium nucleus, which leaves the atom with a net charge of 2-.

Beta emission: a neutron in the nucleus turns into a proton and emits an electron, alon with an electron anti-neutrino. The net charge changes by +1. There's another type of beta decay in which a proton turns into a neutron and emits a positron and an electron neutrino, and the charge goes the other way, but I don't think you'll need to know about that.

Gamma emission: Stuff happens (I forget what) and gamma rays are emitted.

Alpha is highly ionising, but doesn't penetrate far. You can stop it with foil or paper, but f it were to get inside you then you'd be stuffed. Beta is less ionising, but more penetrative, and takes a few centimetres of lead to stop it. Gamma is weakly ionising but highly penetrative, so it could pass through you with ease without stopping to do any harm on the way.

 

[Gammawolf]

Someone say mah name!?

 

[jewii]

ok thanks.

so bottom line is:
"ionisation describes the effect of an atom loosing an electron from one of numerous factors)

 

[TheCenturion]

Ionisation doesn't necessarily mean losing an electron. If an atom gained an electron it would still be ionised.

Ionisation is the process of an atom becoming an ion ( a charged atom) either via losing or gaining at least one electron

 

[Vonhelmet]

Ionisation doesn't necessarily mean losing an electron. If an atom gained an electron it would still be ionised.

Ionisation is the process of an atom becoming an ion ( a charged atom) either via losing or gaining at least one electron

Or by losing or gainin protons. Anything that leaves the charge imbalances, basically.

 

[BetaNumeric]

Ionisation doesn't necessarily mean losing an electron. If an atom gained an electron it would still be ionised.

Ionisation is the process of an atom becoming an ion ( a charged atom) either via losing or gaining at least one electron

Knocking an electron off an atom or molecule is easy, you just have to hit it with something hard enough. Gaining an electron is a delicate process for an already stable molecule.

Gaining an electron is much much more unlikely, as it requires a source of electrons and the system to be stable enough for an electron to be gained, which in itself is an unstable configuration often.

For instance, Chlorine likes to form Cl- ions, to fill its outer shell fully. However, because of this you're unlikely to find Cl sitting on its own in nature, it ends up combining with something to steal one of its electrons in some way, like forming a covalent bond with Hydrogen to get HCl. To add an electron to this configuration is extremely difficult, you have to slot an electron in somewhere, which would require you to break the nice energy stability already there. The system would want to expel the electron almost immediately.

Removing an electron is easier, you just rip it out and the system can't do anything about it if the electron flies off away from it.

Or by losing or gainin protons. Anything that leaves the charge imbalances, basically.

Short of knocking Hydrogen (which has a single proton as its nucleus) out of a molecule how would this occur in anything but staggeringly rare flukes? The sorts of energy levels required to split a nucleus are thousands of times higher than the energy needed to knock an electron off a shell. I'm not saying I know you to be wrong, I'm not a nuclear chemist, I honestly don't see this happening in a regular way like normal ionisation does. If you know a common occurrence of this I'd be interested to know what its called and where/when it occurs.

 

[Vonhelmet]

Short of knocking Hydrogen (which has a single proton as its nucleus) out of a molecule how would this occur in anything but staggeringly rare flukes? The sorts of energy levels required to split a nucleus are thousands of times higher than the energy needed to knock an electron off a shell. I'm not saying I know you to be wrong, I'm not a nuclear chemist, I honestly don't see this happening in a regular way like normal ionisation does. If you know a common occurrence of this I'd be interested to know what its called and where/when it occurs.

Well, as I said in my first post, alpha decay is a helium nucleus leaving the nucleus of its "parent" atom, so this occurs routinely in any radioactive element that decays by way of alpha decay. Alpha decay occurs in large atoms in which a large amount of force is required to hold the nucleus together. As the atom bounces around and the particles in the nucleus move around, every now and then the force can't cope and the particles escape, which has the result of bringing the nucleus more into balance.

Beta decay is a proton turning into a neutron or vice versa, so it doesn't leave the nucleus per se, but the charge does. This is getting beyond my A-level physics knowledge, so I'm cribbing from Wikipedia here. This occurs in overly proton or neutron rich nuclei, in which the forces are again close to tipping point in terms of holding things together. This time, the decay occurs by way of quarks inside the nuclides converting from one kind to another, with the result of bringing the forces more into balance.

 

[jewii]

wow thanks for the feedback. i did already understand all about how Beta,gamma and alpha emissions came about and why. there was just a small section in the specification stating about what is ionising and how does alpha and beta have a role in it.

you can feel free to continue the discussion of about the rest because it is intresting.

But does anyone actually know how an beta and alpha particle actually ionise an atom. thats the data i need to know practically and how gamma ionises to be on the safe side.

whats i've read from here.

The beta particle collides with an electron in the shell of atom and knocks it out of the atom
Alpha either collides with an electron like in beta or attracts the electron out of the shell
Gamma excites the atom heavily to the point where the electrons are so far from the centre of the nuclei that it escapes due to lack of electrostatic forces.

Are these theories correct?

 

[BetaNumeric]

Well, as I said in my first post, alpha decay is a helium nucleus leaving the nucleus of its "parent" atom, so this occurs routinely in any radioactive element that decays by way of alpha decay. Alpha decay occurs in large atoms in which a large amount of force is required to hold the nucleus together. As the atom bounces around and the particles in the nucleus move around, every now and then the force can't cope and the particles escape, which has the result of bringing the nucleus more into balance.

Alpha decay doesn't depend upon the relative motion of the entire atom itself, it is to do with a pair of neutrons and a pair of protons quantum tunnelling through the potential formed by the strong force in the nucleus. The parent atom doesn't hold onto the electrons as far as I'm aware, so it doesn't mean you get X -> Y-- + He++, but rather something more messy where a bunch of electrons are thrown out too. This isn't knocking a proton off though (or even two protons), it's the nucleus disintegrating. Perhaps I just misinterpreted what you meant, as I thought you were talking about knocking a proton off like ionisation can involve knocking an electron off.

Actually, come to think of it there might actually be a common process which does knock out protons. Typing this post has rung a bell in my head about some kind of way of producing either anti-protons or neutrons by sending a beam of protons into some well known material. I'll see if Google knows what I'm trying to remember...

Beta decay is a proton turning into a neutron or vice versa, so it doesn't leave the nucleus per se, but the charge does. This is getting beyond my A-level physics knowledge, so I'm cribbing from Wikipedia here. This occurs in overly proton or neutron rich nuclei, in which the forces are again close to tipping point in terms of holding things together. This time, the decay occurs by way of quarks inside the nuclides converting from one kind to another, with the result of bringing the forces more into balance.

One of the quarks (there's 3, 2 of which are the same, in a nucleon and it is always one of those two) emits a W boson, which decays before it even gets out of the nucleus. In emitting the W boson it turns into a different type of quark (to march the other quark already in the nucleon). The W decays into a lepton (in beta decay its an electron and in inverse-beta decay its a positron) and the corresponding anti-neutrino and those are what we measure. I suppose inverse beta decay doesn't 'knock a proton out' but rather converts it into a neutron.

Neutrons, if outside a nucleus, turn into protons via beta decay with something like a half life of 11 minutes. It's not currently well understood how being in a nucleus with other protons and neutrons stabilises them. Good job it does though or we'd not be here

 

[BetaNumeric]

But does anyone actually know how an beta and alpha particle actually ionise an atom. thats the data i need to know practically and how gamma ionises to be on the safe side.

whats i've read from here.

The beta particle collides with an electron in the shell of atom and knocks it out of the atom
Alpha either collides with an electron like in beta or attracts the electron out of the shell
Gamma excites the atom heavily to the point where the electrons are so far from the centre of the nuclei that it escapes due to lack of electrostatic forces.

Are these theories correct?

They all basically slam into either an electron orbiting the nucleus or the nucleus itself (that's only gamma radiations IIRC, as photons aren't affected by the charges of the electron shells or nucleus) and that results in bits being chipped off.

Because alpha particles can strip electrons from other atoms by virtue of their +2 charge they easily get affected by material, which is why they can be stopped by something as simple as a bit of paper or skin. Once its captured 2 electrons it can only affect things by hitting them directly.

Beta particles don't attract electrons (since they are electrons) but they can still scatter off them, in the way two magnets of the same polarity push one another away from each other. Typical beta decay energies (ie a measure of how fast the particle is emitted) vastly exceed the energy needed to push an electron out of orbit and hence a single beta emission can knock electrons from many atoms until it finally runs out of juice. This can be seen in bubble chamber pictures.

Gamma particles are photons, they don't feel the charge of the electrons or nuclei so they work by direct collisions. Because of this they don't lose energy gradually, unlike the other two which can be slowed by being pushed about by the forces from other particles, so the first thing they hit gets the full punch and that punch is formed by the energy of a nucleus, which is way more than you need to strip an electron from an orbital. It's enough to give even an entire nucleus a kick, as you mention.

Though perhaps too much detail for GCSE/A Level the interaction of electrons with electrons or photons with electrons or nuclei are covered by breamsstrahlung and Compton scattering, leading to gamma spectroscopy.

 

[Vonhelmet]

Alpha decay doesn't depend upon the relative motion of the entire atom itself, it is to do with a pair of neutrons and a pair of protons quantum tunnelling through the potential formed by the strong force in the nucleus. The parent atom doesn't hold onto the electrons as far as I'm aware, so it doesn't mean you get X -> Y-- + He++, but rather something more messy where a bunch of electrons are thrown out too. This isn't knocking a proton off though (or even two protons), it's the nucleus disintegrating. Perhaps I just misinterpreted what you meant, as I thought you were talking about knocking a proton off like ionisation can involve knocking an electron off.

OK, so you're getting a bit technical on me now

My point with regard to the ionisation is that the resulting atom will be ionised by virtue of the fact that the disintegrating atom has lost two protons. As such, it will be two electrons up compared to the number of protons in the nucleus.

 

[FluffySheep]

OK, so you're getting a bit technical on me now

My point with regard to the ionisation is that the resulting atom will be ionised by virtue of the fact that the disintegrating atom has lost two protons. As such, it will be two electrons up compared to the number of protons in the nucleus.

***Off topic slightly...

Problem is as the alpa particle flies out one direction, the remaining nucleus flies at the opposite direction (conservention of momentum) and usually becomes ionised as it looses some of it's outer electrons because of this acceleration.

FluffySheep

 

[James24]

losing protons is not ionisation.

An ion of an atom just has different number of electrons.

Change in protons is due to beta decay where a neutron changes into a proton or vice versa (beta minus, beta plus).

This occurs when the nucleus is unstable (see line of stability). A nucleus likes a nice ratio to be stable. If it not stable decays will occur.

 

[Vonhelmet]

losing protons is not ionisation.

An ion of an atom just has different number of electrons.

Change in protons is due to beta decay where a neutron changes into a proton or vice versa (beta minus, beta plus).

This occurs when the nucleus is unstable (see line of stability). A nucleus likes a nice ratio to be stable. If it not stable decays will occur.

But if it loses protons then it becomes a different atom, and will have the wrong number of electrons (albeit briefly, per the post above!) for that atom.

Surely?