Half-life

Since we are made of a bunch of atoms, do we have a half-life based on  the probabilistic exponential-decay process?  I think it's true that the longer we wait, the less remains.    I hated Chemistry class when I was in high school.  But I know that NaCl+H2So4 yields NaHSo4+HCl yielded as a gas.  I still haven't been able to put that formula to use, except for its helping me to score about 4 points on the mid-term exam, which unfortunately didn't matter all that  much.