Question

which of the following pair of element would have a negative electron gain enthalpy O and F F and CL​

Answer 1

Answer:

That's why electron gain enthalpy of Cl is higher than F. Oxygen and fluorine both belongs to 2nd period. Electron gain enthalpy generally becomes more negative across period when we move from left to right.

Answer 2

Answer :

NEGATIVE ELECTRON GAIN ENTHALPY :

It's the amount of energy released when an electron is added to its valence shell .It increases across the period from left to right because from left to right the effective nuclear charge increase and atomic size decrease and more amount of energy will released from a small atom in compare to large atom, there for down the group Electron Gain Enthalpy decrease as the atomic size increase.

(Fluorine have highest Electron Gain Enthalpy in the periodic table)

So, Fluorine (F) have more Electron Gain Enthalpy then oxygen (O) and Chlorine(C).