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During a group discussion, a student argued that ionization enthalpy depends only upon electronic configuration. 1. Do you agree? Comment. 2. Define shielding effect/screening effect. 3. Is there any relation between ionization enthalpy and shielding effect/screening effect? Explain. |
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Answer» 1. No. In addition to electronic configuration, ionization enthalpy depends upon other factors like atomic size, nuclear charge and shielding effect/screening effect. 2. In multi-electron atoms, the nuclear charge experienced by the valence electron will be less than the actual charge on the nucleus because it is shielded by inner core of electrons. This is called shielding effect or screening effect. 3. Yes. Ionization enthalpy decreases with increase in shielding effect/screening effect of inner electrons. This is because as a result of shielding of the valence electron by the intervening core of electrons it experiences a net positive charge which is less than the actual charge of the nucleus. In general, shielding is effective when the orbitals in the inner shells are completely filled. |
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