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is the electron gain enthalpy and electron affinity the same or different????

is the electron gain enthalpy and electron affinity the same or different????

Grade:10

1 Answers

Aarti Gupta
askIITians Faculty 300 Points
8 years ago
Electron gain enthalpy is the tendency of an gaseous atom to form anion.It is defined as the enthaply change taking place when an isolated gaseous atom accepts an e- to form monovalent gaseous anion.It may be expressed as--
A(g) + e-- ----------------> A-(g) deltaH = deltaegH
Now this process of adding an e- can either be exothermic or endothermic which depends on element.Large -ive value of e- gain enthalpy reflects the greater tendency of an atom to accept the e-.For ex- halogens have very high -ive gain enthalpies because by gaining just 1e- they can attain noble gas configuration but noble gases have large positive gain enthalpies because the additional e- goes to the next principal shell resulting in a very unstable electronic configuration.
Energy changes in the above process can also be represent in terms of electron affinity,which is generally taken to be equal to the --ive of the e- gain enthalpy.
1).If the energy is released on adding an e- to the gaseous atom,then e- affinity is taken as positive.
2).If the energy has to be supplied when an e- is added then e- affinity is taken as negative.

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