if stuff is radioactively decaying, then what happens when it completely decays?

It becomes another element until it is stable. Example polonium usually decays into lead very quickly. Radioactivity is basically instability at the atomic level which is found in alpha beta and gamma forms, it decays until it becomes a non-radioactive element.

This post was edited by Jazz_Thing on Apr 1 2009 12:19pm

not neccessarilly
this is typical for alpha decay where a large nucleus (typically heavier elements like your example) loses a helium nucleus.
however beta and gamma decay dont ever lose protons and thus dont change elements

there are also other types of decay (though i dont think they fall under "radio active")
such as the decay of a proton into a neutron. this sometimes occurs during the the death of large stars and the birth of neutron stars when the matter collides to the core of a star and protons either emit positrons, or capture electrons giving neutrons and neutrinos. this is the rapid decay that makes neutron stars composed of completely (or nearly completely) neutrons

anyways, jazz is correct. the process goes to completion until the molecule is stable. simply put, when its done decaying, it just stops and is just equivilent to a molecule who is not radioactive

This post was edited by Kamikizzle on Apr 1 2009 02:43pm

:huh:

Man, not another one.

Ooohh, of course.

Uhh. Beta decay causes an element change. A neutron decays and splits into a proton and electron and emits the electron. In short, although it can also turn a proton and a captured electron into a neutron. Or positron emission which is a type of beta radiation causes a proton to split into a positron and a neutron

I guess you said all that, but it is quite common and IS considered beta decay.