Consider the specific second-period elements: and . Exactly how many of these elements possess a str — Periodic Table and Periodicity Chemistry Question

💡 Solution & Explanation

A positive first electron gain enthalpy occurs when adding an electron disrupts a highly stable electronic configuration. Among the given elements, Beryllium ($Be$) has a fully filled stable $2s^2$ subshell, and Nitrogen ($N$) has a highly stable, exactly half-filled $2p^3$ subshell. Both resist accepting an extra electron. The rest have exothermic (negative) first electron gain enthalpies. Total = 2.