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What is thesignificanceof the terms ' isolatedgaseousatom' and' groundstatewhiledefiningtheionizationenthalpy and elecron gain enthalpy ? |
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Answer» Solution :(i) Ionizationenthalpyis theminimumamount of theenergyrequiredto remove themostloosely boundelectrons increases isolatedgaseous atom so as to convert it into a gaseouscation. The forcewithwhichan ELECTRON isattractedby the nucleus of an atom isappreciablyaffected bypresence ofotheratomswithinit molecule or in theneighbourhood. Therefore for the purposeof determination of theionizationenthalpy it isessential that these interatimic forces of attraction should be minimum . sincein thegaseous state theatom arewidely separated thereforetheseinteratomicforces areminimum. furthersince it is not possible to isolatea singleatom for the purpose ofdetermination of its ionization enthalpy therefore, the interatomic distancesare furtherreduced by carrying out themeasurementat a lowpressure of the gaseous atom,. It isbecause of theseresons that theterm isolated gaseousatomhas beenincludedin the definition of ionization enthalpy. (ii)Electron gainenthalpy is theenergyreleasedwhen anisolatedgaseousatom in thegroundstate acceptsan extraelectronto formthe gaseousnegative ion. Thetermisolatedgaseous atom has laready beenexplained above. thetermgroundstateheremeans that the atom mustbe present in themost stablestate i.e.,the GROUND state. Thereason beingthatwhen the isolatedgaseousatom isin the EXCITED state LESSER amount of energy will bereleasedwhen itgets converted into gaseous anion after ACCEPTING an electron. Thereforefor comparisonpurposes, the electron gainenethalpies ofgaseous atom must bedetermined in theirrespectivemoststablestate i.e.,ground state. |
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