flex20 - 19-10-2003 at 12:26
vulture - 19-10-2003 at 12:36
I've noticed that you posted several one line questions. Please provide more info/be more specific. Furthermore, I might be wrong, but these
questions make the "please-make-my-homework-alert" go berserk.
I find it said that people just want to get answers without putting any effort into it themselves, especially when they are abusing the benevolence
and enthusiasm of people who like the subject.
Jay Maity - 25-1-2004 at 06:46
As far as I know the most haviest element which is stable is 82Pb206.
Mumbles - 25-1-2004 at 10:45
The lightest is obviously protium(Hydrogen-1). Something tells me that there is a bismuth isotope that is stable. We learned that Lead-206 was in
school, but I was reading and I believe it said that an isotope of Bismuth(209) was stable.
[edit] I had it backwards. Bismuth-209 was considered the heaviest stable element, but it was found to be radioactive. Longest half-life of any
element.
Heres the article: http://physicsweb.org/article/news/7/4/16
[Edited on 1-25-2004 by Mumbles]
Pyrovus - 28-1-2004 at 17:45
Actually, current theory suggests that even protium may be unstable - it is thought that protons decay with a half life of something like 10^30 years.
Blind Angel - 28-1-2004 at 19:03
that make me wonders, will the universe goes as far as 10^30 years old? It's actualy a pretty big number, even if a year is nothing in
astronomical term...
Mumbles - 28-1-2004 at 20:36
I don't think any of us will ever find out, unless some one can find a solution to Eternal life topic from a while ago. Hopefully he/she is from
this board and distributes it freely amonst ourselves. Then we can have an ultimate race of Mad Scientists ruling the world.
Watch, the answer is to live in an atmosphere of HF, HCN, NOx, and Ethyl Mercaptan or something equally as revolting. If I had to live in skunk
stench I wouldn't want to live for 10^30 years.
Pyrovus - 30-1-2004 at 19:33
You probably don't need to hang around for 10^30 years to find out if the universe lasts that long. All you need is to find out the average
density of the universe. If it is greater than the critical value, the universe will eventually recollapse. If it is equal to this value it will slow
down in it's expansion, tending asymptopically to a certain size. And if it's less than that value the universe will continue expanding
forever. Of course, after 10^30 years all matter within it will be so thinly spread that the universe will likely be an incredibly boring place.
There'll still be a few black holes and things, but they'll all be gone in about 10^66 years.
JohnWW - 27-7-2004 at 17:09
I saw on another thread that the half-life of Bi-209 was found to be something like 2 x 10^19 years, many times the age of Earth and indeed many times
the 13.7 billion year estimated age of the matter in the universe(whether or not there was a big bang). It decays by alpha-emission to Tl-205. With
such a long half-like, its radioactivity is practically undetectable.
Thorium-232 and uranium-238, with half-lives at least the age of Earth, come very close to stability. Their toxicity is chemical, not due to
radioactivity.
The theoretics of "magic numbers" in the filling of shells of protons and neutrons of superheavy elements indicate that element 114 with
atomic weight 298, and possibly element 115 with atomic weight 299, should be stable or almost so, having 184 neutrons. There are the both nuclear
and chemical homologs of Pb-208 and Bi-209. Isotopes of these elements have been made recently e.g. by bombarding plutonium-244 with calcium-48, but
they were severely neutron-deficient (by about 10 neutrons) compared to the number of neutrons required for stability.
John W.