; kJ mol

; kJ mol

Thus the process of formation of is unfavorable even though is isoelectronic with neon. It is due to the fact that

Question

;  kJ mol

Thus the process of formation of  is unfavorable even though  is isoelectronic with neon. It is due to the fact that

Canvas Classes · Accepted Answer

Strategy:
 Analyze why achieveing a noble gas configuration is not always favorable in a single isolated step.

Step 1: Analyze the values
- Stage 1:  (Exothermic, ).
- Stage 2:  (Endothermic, ).

Step 2: Explain the unfavorability
While  is stable in ionic crystals due to lattice energy, adding an electron to the already negatively charged  ion in the gas phase is hard. The strong electrostatic repulsion between the negative ion and the incoming electron consumes more energy than achieved by no

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