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प्रश्न
Explain the following:
Ionisation enthalpy decrease in a group from top to bottom?
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उत्तर
On moving down a group there is a gradual decrease in ionisation enthalpy. The decrease in ionisation enthalpy down a group can be explained in terms of net effect of the following factors:
(i) In going from top to bottom in a group, the nuclear charge increases.
(ii) There is a gradual increase in atomic size due to an additional main energy shell (n).
(iii) There is increase in shielding effect on the outermost electron due to increase in the number of inner electrons.
The effect of increase in atomic size and the shielding effect is much more than the effect of increase in nuclear charge. As a result, the electron becomes less and less firmly held to the nucleus as we move down the group. Hence, there is a gradual decrease in the ionization enthalpies in a group.
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संबंधित प्रश्न
Energy of an electron in the ground state of the hydrogen atom is –2.18 × 10–18 J. Calculate the ionization enthalpy of atomic hydrogen in terms of J mol–1.
Hint: Apply the idea of mole concept to derive the answer.
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order Li < B < Be < C < O < N < F < Ne.
Explain why Be has higher ΔiH than B?
Among the second period elements the actual ionization enthalpies are in the
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Explain why O has lower ΔiH than N and F?
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| B | Al | Ga | In | Tl |
| 801 | 577 | 579 | 558 | 589 |
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Would you expect the first ionization enthalpies for two isotopes of the same element to be the same or different? Justify your answer.
Which one of the following statements is incorrect in relation to ionization enthalpy?
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(i) 2
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(iii) 1
(iv) 17
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