Question

3. Determine the Zeff value of Uranium, also indicate (based on your answer with mathematical calculations) which electron will be closest to the nucleus of this element: 5s, 5p, 5f or 5d.

Answer 1

Explanation:

Electronic configuration of uranium is given below -

1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶4d¹⁰5s²5p⁶4f¹⁴5d¹⁰6s²6p⁶5f³6d¹7s2²

Effective nuclear charge (Z eff) = Atomic number (Z) - Shielding constant (S)

Value of Shielding constant (S) can be calculated by using slater's rule :

S = 1 (0.35) + 9 (0.85) + 81 (1.00)

S = 0.35 + 7.65 + 81.00

S = 89

So,

Zeff = Z - S

Zeff = 92 - 89

Zeff = 3

Hence, Effective nuclear charge (Zeff) of uranium = 3

5s electron is closest to the nucleus.