Elemental half-life: novel idea?

[zforgetaboutit]

I was wondering if there were any known solid elements, natural or synthetic, which radioactively decay into a gas.

It would be cool to watch a block of it become more and more sponge-like, and therefore less dense, as it decayed - structurally crumbling until finally no solid could be observed with the naked eye.

Quick, somebody give me a dry ice Meccano Erector set.

 

[chroot]

Quite a lot of radioactive elements decay into radon gas as some point on their way down to stability.

However, these same elements also decay via a lot of other mechanisms into a variety of other substances, not just radon.

- Warren

 

[HallsofIvy]

Radium is one such. However, I would not advise sitting and watching a solid lump of a radioactive material "dissolve" as a hobby. Any thing with a short enough half life that you could actually SEE something happen would be so "hot" you probably wouldn't live to give us a report on it!

 

[swansont]

All you have to do is find an element that's a solid that's next to a gas on the periodic table, and then find an isotope that undergoes the appropriate beta decay. Or two steps away, and alpha decay (gas being lighter). There have to be hundreds of candidates. Obtaining one of them is the big obstacle. If it's naturally occurring, chances are the half-life is reeeaaally long, so it's not going to put on much of a show. If the half-life is short enough to see this happen, then it'll be tough to get macroscopic amounts, and it'll have a big activity.