Concept:The conversion of a neutral atom into a positively charged ion (cation) involves the removal of an electron. This is quantified by the Ionization Energy.
Formula:$$ Na_{(g)} + \text{Energy} \rightarrow Na^+_{(g)} + e^- $$
Solution:- Electrons are held in orbit by the electrostatic attractive pull of the positive nucleus.
- To overcome this attraction and remove the valence electron from a sodium atom, a strict input of energy is required.
- Because energy must be absorbed from the surroundings to drive the process, it is strictly an endothermic process (\( \Delta H = +\text{ve} \)).
Why other options are incorrect:It is never exothermic because stripping an electron from an atom always requires energy. Sublimation refers to solid converting to gas, not ionization.
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