Sciencemadness Discussion Board

Bismuth dethroned as heaviest stable element.

I am a fish - 25-4-2003 at 13:29

Bismuth 209 – the only naturally occuring isotope of the element – has been found to be an alpha emitter. It's half-life is by far the longest known – (1.9 +/- 0.2) x 10^19 years. This leaves lead as the heaviest stable element.

Nick F - 27-4-2003 at 03:37

LOADS of things are long half-life alpha emitters. A few that spring to mind are (IIRC, I can't find the website) tungsten, germanium, neodymium (about half the lanthanides, actually), zinc too I think, a goodly portion of d-block metals....
It just depends on where you draw the line between stable and instable. Just because you might not detect a single decay from a ton of material over a billion years, does not mean that it never decays but I think we would call it stable!

Microtek - 27-4-2003 at 09:10

In fact, even protons ( and thus all matter ) decays with a half life of 10^32 years.

Blind Angel - 27-4-2003 at 10:44

if all decay to the simpliest form, does they regenerate also?

Nick F - 27-4-2003 at 11:56

Microtek, I think protons would be like neutrons in that they decay only outside the nucleus, due to quarks moving and swapping around and this keeps them stable (another concise explanation there ;)).
I haven't been keeping up-to-date on my physics, last time I checked the proton was still stable. Just like benzene used to be safe.

AndersHoveland - 20-9-2011 at 13:45

Quote: Originally posted by Nick F  
LOADS of things are long half-life alpha emitters. tungsten, germanium, neodymium (about half the lanthanides, actually), zinc too I think, a goodly portion of d-block metals....
It just depends on where you draw the line between stable and instable. Just because you might not detect a single decay from a ton of material over a billion years, does not mean that it never decays but I think we would call it stable!


Is this really true?! Not all of the naturally occuring isotopes of tungsten and germanium actually radioactive. wikipedia says that 70Ge, 72Ge, 73Ge, 74Ge are all stable.

[Edited on 20-9-2011 by AndersHoveland]

phlogiston - 20-9-2011 at 14:48

Microtek, protons are not unstable.
In fact, this is an important issue in particle physics. Observing proton decay would provide clues to 'new' physics beyond the standard model, and has therefore been rigorously investigated. So far, no observationsof proton decay have been made. The half life you mention (10^32) is actually the -lower limit- of proton half life determined from the experiments so far. (i.e. nobody observed any proton decay events in a volume of such and such, over a time span of ..., etc).

blogfast25 - 21-9-2011 at 04:50

Quote: Originally posted by phlogiston  
Microtek, protons are not unstable.
In fact, this is an important issue in particle physics. Observing proton decay would provide clues to 'new' physics beyond the standard model, and has therefore been rigorously investigated. So far, no observationsof proton decay have been made. The half life you mention (10^32) is actually the -lower limit- of proton half life determined from the experiments so far. (i.e. nobody observed any proton decay events in a volume of such and such, over a time span of ..., etc).


Cosmologists accept the universe will eventually decay to radiation soup. We just haven't up to now been able to observe a single proton decay, at least as far as I know...

dann2 - 21-9-2011 at 06:32

Quote: Originally posted by I am a fish  
.......years. This leaves lead as the heaviest stable element.


Three cheers for LEAD.
All together now, hip hip...........

Dann2

simba - 21-9-2011 at 07:38

Quote: Originally posted by blogfast25  

Cosmologists accept the universe will eventually decay to radiation soup. We just haven't up to now been able to observe a single proton decay, at least as far as I know...


I think the topic's name should be changed to 'How the universe will end?' or 'How do you picture the apocalypse'. :P

[Edited on 21-9-2011 by shivas]

AndersHoveland - 21-9-2011 at 19:10

I see the universe as cyclical, everything is headed towards how it was before.

I am not sure if everything will be swallowed up by a super-massive black hole, but if it is, I think this would warp space-time enough that the black hole would be able to explode, starting the next "big bang".