Which one of the following arrangements represents the correct order of least negative to most negative…

Which one of the following arrangements represents the correct order of least negative to most negative electron gain enthalpy for $\mathrm{C}, \mathrm{Ca}, \mathrm{Al}, \mathrm{F}$ and $\mathrm{O} ?$
  1. $\mathrm{Ca} < \mathrm{Al} < \mathrm{C} < \mathrm{O} < \mathrm{F}$
  2. $\mathrm{Al} < \mathrm{Ca} < \mathrm{O} < \mathrm{C} < \mathrm{F}$
  3. $\mathrm{Al} < \mathrm{O} < \mathrm{C} < \mathrm{Ca} < \mathrm{F}$
  4. $\mathrm{C} < \mathrm{F} < \mathrm{O} < \mathrm{Al} < \mathrm{Ca}$

Solution

As the nuclear charge increases, the force of attraction between the nucleus and the incoming electron increases and hence the elecron gain enthalpy becomes more negative, hence the correct order is $\mathrm{Ca} < \mathrm{Al} < \mathrm{C} < \mathrm{O} < \mathrm{F}$

Asked in: JEE-TOPICTESTS-CHEMISTRY

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