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(a) What is the significance of the term "isolated gaseous atom" while defining ionization enthalpy? (b) Na and Mg+ have the same number of electrons but removal of electron from Mg+ requires more energy. Give reason. (c) Elements in the same group have similar chemical properties. Give reason. |
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Answer» (a) In the gaseous state, the atoms are widely separated, therefore, interatomic forces are minimum. It is because of this reason the term 'isolated gaseous atom' has been included in definition of ionization enthalpy. (b) The effective nuclear charge increases across a period. Both Na and Mg+ has same numbers of electrons in outermost shell, but Mg+ has more effective nuclear charge than Na. As the effective nuclear charge increases, the hold of the nucleus on the outermost electrons will also be increased. Thus, it will be very difficult to remove the electrons for outer most shell. That's why it is difficult to remove electron from Mg+ as compared to Na. (c) Elements in the same group in the periodic table have similar chemical properties because their atoms have the same number of electrons in the highest outermost shell. |
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