Question

Why tritium is radioactive?

Answer 1

uhh...that's not a good reason .. i'm asking why tritium is radioactive?? why it is unstable???

Answer 2

An isolated particle can only decay into particles which are less
massive than the original particle. The rest mass energy of the
original particle E=mc^2 is converted into the masses of the decay
products and also into their kinetic energies. The decay must
conserve energy, linear momentum, angular momentum, electric charge,
lepton number, and baryon number.

The tritium nucleus, or triton, is unstable simply because it is more
massive than its decay products which are a helium-3 nucleus, an
electron, and an electron anti-neutrino. This is called beta decay
because an electron ejected from the nucleus was named a beta
particle by early researchers. Symbolically,

3 3 0 _
H --> He + e + v + kinetic energy
1 2 -1

where the superscripts label the "atomic mass" A which is the number
of nucleons (proton and neutrons), while the subscripts label the
"atomic number" Z which is the charge in units such the proton charge
is +1.
for more visit
http://www.madsci.org/posts/archives/2003-06/1054474286.Ph.r.html