Two atoms are walking down the street

The first atom says to the second atom "I think I lost an electron!" The second says "Are you sure?" To which the first states "I'm positive!"

Two isotopes are walking down the street... One has a half-life of 424,000 years, and one has a half-life of 420,000 years. What did the former say when the latter died?

"Still alive!"

Ha ha ha.