f6 chem

Question:

Account for the difference in ionzation enthalpies between K and Cu.

1st I.E. : 418 kJ mol-1

1st I.E. : 745 kJ mol-1

Ans:

Although Cu has 10 more photons and 10 more electrons than K, the 10 electrons are in the less penetrating 3d subshell so that they do not screen the 4s electron effectively . The 4s electron of Cu experiences a large effective nuclear charge than the 4s electron of K. Therefore the 1st I.E. of Cu is larger than that of K.

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Update:

K 1st I.E. : 418 kJ mol-1

Cu 1st I.E. : 745 kJ mol-1

1 Answer

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  • 1 decade ago
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    K : [Ar] 4s1Cu: [Ar] 3d104s1 You can see that the difference is…..Cu contains 10 more electrons than K. ∵ repulsive effect à the extent of diffusion of d-electron↑à shielding effect↓ ∴ 4s electron in Cu does not shielding effectively by the 3d electrons

    However, (Cu) its effective nuclear charge increased by 10à shielding effect by 3d electrons is weakà shielding effect is not predominate when compared with the effective nuclear chargeà stronger electrostatic attraction between the nucleus & the 4s electron than that of K

    Source(s): 撼頭埋牆
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