From: Ronald Wong (ronwong@inreach.com)
Date: Thu Sep 02 2004 - 23:32:32 PDT
Message-Id: <l03102800bd5b35b2a485@[209.209.18.107]> Date: Thu, 2 Sep 2004 23:32:32 -0700 From: Ronald Wong <ronwong@inreach.com> Subject: Re: physcial change & why CO2 douses flames
While browsing through Pinhole's archive, I noticed that some interesting
questions have gone unanswered.
Here's a series from Treena Joiful in April of this year:
>...
>I guess I thought of a third question .. with the Rutherford Rollers
>activity I am able to be more convincing about atomic structure
>consisting of so much space, but then they want to know where the alpha
>particles came from
In Rutherford's days, the source of alpha particles were radioactive
materials found in nature such as radium.
This is the same stuff that was put in the paint used
to form the luminous elements of a clock or watch face
during the first half of the last century. The paint
had phosphorescent material that would absorb the alpha
particles and convert their energy into light. I had a
clock face from the 50's in my classroom that was a
great source of alpha particles and was still quite
luminous in the 80's - talk about hazardous waste material!
Uranium, thorium,
The mantles in the gas-burning camping lanterns use to be
made of thorium oxide but no more. They turned into a pile
ash when damaged and the ash, when inhaled, increased the
likelihood of getting lung cancer due to the alpha
particles created by the thorium atoms as they mutated
into the gas called radon - which itself is a naturally
occurring alpha emitter.
and polonium will produce alpha particles when they decay.
In the past, the anti-static brushes that were used to clean
negatives and slides contained polonium to neutralize
any electrical charge that was created by the brushing.
A source of alpha particles that isn't naturally occurring can be found in
many places nowadays. It's an element called americium. It's transuranic
and can be found in most of the smoke detectors found in homes today.
>and how to shoot them
Rutherford took a block of lead and drilled a long hole in it. Into the
hole he dropped a piece of radium. Only the alpha particles emitted in the
direction of the hole streamed out of the block.
>how to detect them.
Fluorescent material such as zinc sulfide will give off light when alpha
particles fall on it. I believe that's what Rutherford used in his
experiment.
*****************************
Treena probably knows all of this by now but, hopefully, some of you will
have found this informative.
Caio!
ron
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