[constant thinker]

I see ?- and ?- all the time. The problem is I don't know what they mean. Can someone please help.

[Mitch]

very vague question

[Emas]

I think you might be referring to alpha and beta particles.

a is an ⁴₂He nucleus. it is emitted during radioactive decay and is able to be stopped by a sheet of paper & it travels at 10% of the speed of light. it only travles a few centimetres in the air.

? is a ⁰_-1e i.e. a highly charged electron that travels at 90% of the speed of light. and can be stopped be aluminium a few centimetres thick. These can travel up to 30cm in the air.

I hope this is what you were after. The question wasnt very clear...

[Borek]

In what context do you see them?

[xiankai]

 i thought alpha particles were the equalivent of a helium nucleus, but NOT a helium nucleus itself?

same goes for beta, i also thought it was just an equalivent of an electron :/ and do electrons really travel that fast? i heard soemwhere that elctrons move slow, like a few cm per sec.

[Borek]

i thought alpha particles were the equalivent of a helium nucleus, but NOT a helium nucleus itself?

That's exatcly the same particle - two neutrons and two protons.

same goes for beta, i also thought it was just an equalivent of an electron

As above - it is just an electron.

and do electrons really travel that fast? i heard soemwhere that elctrons move slow, like a few cm per sec.

It depends. cm/s is a translational speed of electron in the wire in the lamp on your desk. Electron in accelerator can be accelerated almost to speed of light.

[Corvettaholic]

About the beta particles, I thought it was more than just an electron. Read somewhere that its an electron AND an anti-neutrino? But as I understand it, neutrino's will just zip right through anything and they're good for nothing particles currently. Just kinda neat to watch them exist.

[Donaldson Tan]

beta particles also refer to positrons, ie. anti-electrons

in organic chemistry, alpha and beta are carbon positions.

[movies]

Some other places alpha and beta show up:

- Sign of electron spin in quantum mechanics
- proximity to a certain atom or functionality (e.g. the alpha carbon of a carbonyl group, alpha,beta-unsaturated carbonyls, beta-hydride elimination in organometallic chemistry)
- antiquated method of describing stereochemistry at a chiral center (If the structure is drawn such that the functionality in question goes back into the page, it is alpha, if the functionality comes out of the page, it is beta.  Note that this descriptor depends entirely on how the structure is drawn.)

[Borek]

About the beta particles, I thought it was more than just an electron. Read somewhere that its an electron AND an anti-neutrino?

Beta particle is just electron. Some kind of neutrino is a byproduct of beta decay.

[constant thinker]

I can't find the website that triggered me to ask the question. It was talking about nuclear decay though so it probably refers to the alpha and beta particles. I realized it was vague and apoligize. I should have quoted the website when I started this. Thanks.

Would anyone happen to know what gamma radiation is made of? I've only read it was energy released during the realignment of the nucleus not what it was made of.

[jdurg]

Gamma rays are basically high energy photons.  The nucleus emitting a gamma ray is akin to an excited electron emitting a wavelength of light when it falls back down into the ground state.  In a nuclear reaction, the nucleus winds up in an excited state when a decay occurs, so it will shoot off a gamma ray as it settles back into a ground state.  Thinks of a gamma ray as a VERY high energy, VERY short wavelength of light.

[constant thinker]

Ok. Cool thanks for the help.