Darkness: Umm, no.
If something has a halflife of 1 year, what that means is that any given atom has a 50% chance of decaying over the period of a year.
So, given the amount of atoms in even a tiny sample of substance, over 1 year the laws of chance dictate that you're practically certain to get very nearly 50% of the substance decaying.
Eventually you'll get down to one atom ... then, there's a 50% chance that the atom will decay within one year and there'll be no original substance left.
If it doesn't ... well, 50% chance it'll decay the year after that
And so on...it COULD last forever, but it aint likely.
Mathematically speaking, if you LITERALLY halved something, you might have to split an atom, but a half life isn't a literal, exact, halving of the substance ... it's an approximation; but given the number of atoms you're dealing with it tends to average out to almost exactly 50%.