Ever had that existential crisis when you discover certain atomic masses are just doomed to be unstable? Nuclear physics doesn't care about your feelings! Those specific nuclides (5, 8, 147, 151) are all radioactive because their nuclear configurations are fundamentally unstable - Mother Nature's way of saying "this arrangement just won't work long-term." It's like trying to balance a pencil on its tip - theoretically possible, but physics is gonna physics. The universe has trust issues with these particular atomic arrangements!