Which among the following elements has the highest electron gain enthalpy with negative sign in the periodic table?

💡 Solution & Explanation

Chlorine possesses the highest negative electron gain enthalpy in the periodic table because fluorine's extremely small compact atomic size creates high electron-electron repulsion, which hinders the incoming electron. Electron gain enthalpy becomes more negative across a period and decreases in magnitude down a group, with notable anomalies in the second period. This property measures the amount of energy released when an isolated gaseous atom accepts an electron. Halogens generally exhibit high negative electron gain enthalpies due to their proximity to a stable noble gas configuration.