Natural radioactivity is universally observed when the neutron-to-proton () ratio exceeds a specific — Nuclear Chemistry and Radioactivity Chemistry Question

💡 Solution & Explanation

Elements with low atomic numbers ($Z < 20$) are stable at $n/p = 1$. This ratio gradually increases to about $1.52$ for the heaviest stable elements. Any nucleus with an $n/p$ ratio exceeding roughly $1.52$ (or $Z \ge 84$) falls outside the stability zone and is radioactive.