Question

Find out the effective nuclear charge for 3d electron for chromium atom (z=24)

Answer 1

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The formula to be used is: 

Z* = Z - S 

where: 
Z* = effective nuclear charge 
Z = atomic number of Cr = 24 
S = shielding 

Let us first calculate S using Slater's rule. 

*Write the electronic configuration as follows: (1s)^2 (2s 2p)^8 (3s 3p)^8 (3d)^5 (4s)^1 

*Electrons in an "s" or "p" orbit in the same shell as the electron for which you're solving contribute 0.35, electrons in an "s" or "p" orbital in the shell one energy level lower contribute 0.85, and electrons in an "s" or "p" orbital in shells two energy levels and lower contribute 1.

Therefore, the (4s)^1 do not contribute since we are focusing on the 3d orbital. Therefore, 

S = (5 x 0.35) + (8 x 0.85) + (10 x 1) = 18.55 

Thus, 

Z* Z - S = 24 - 18.55 = 5.45 

* Electrons in a "d" or "f" orbital in the same shell as the electron for which you're calculating contribute 0.35, and electrons in an "d" or "f" orbital in all lower energy levels contribute 1. Electrons in shells higher than the electron for which you're solving do not contribute to shielding. 

Therefore, the (4s)^1 do not contribute since we are focusing on the 3d orbital. Therefore, 

S = (4 x 0.35) + (18 x 1) = 19.4 

Thus, 

Z* = 24 - 19.4 = 4.6 

$\boxed{Hope\:This\:Helps}$

Answer 2

Answer:

The correct answer is 4.60.

Step by step Explanation :

The formula for calculating the effective nuclear charge for a single electron is:

Zeff= Z − S

Zeff is the effective nuclear charge.

Z is the atomic number.

S is the average amount of electron density between the nucleus and the electron.

The atomic number of chromium is 24.

S requires the use of Slater’s Rules to determine the value.

For chromium, the electron configuration is (1s2) (2s2, 2p6) (3s2 3p6) (3d5) (4s1).

Any electrons to the right of the electron of interest contain no shielding value.

Therefore (4s)1 do not contribute since we are focusing on the 3d orbital.

Electrons in the same group as the electron of interest shields 0.35 nuclear charge units.

For d or f electrons: all electrons shield 1.00 unit.

Zeff =24−(4×0.35)−(18×1).

Zeff = 24 - 19.4 = 4.6