Question

Part A) What value do you estimate for Zeff experienced by the outermost electron in both Na and K by assuming core electrons contribute 1.00 and valence electronscontribute 0.00 to the screening constant?

Part B) What values do you estimate for Zeff using Slater's rules?

Part C) Which approach gives a more accurate estimate of Zeff ?
1. The first method.
2. The second (Slater) method.


Part D) Does either method of approximation account for the gradual increase in Zeff that occurs upon moving down a group?
1. Yes, both methods account for the gradual increase in Zeff.
2. Yes, the first method accounts for the gradual increase in .
3. Yes, the second method accounts for the gradual increase in .
4. No, neither of the methods above accounts for the gradual increase in

Part E) Predict for the outermost electrons in the atom based on the calculations for and .
Express your answer using two significant figures.

Answer 1

For Na (1S)^2 (2S,2P)^8 (3S)^1
Zeff=Z-S S= (2 x 1.0) + (8 x0.85) = 8.8
Zeff = 11 - 8.8 = 2.2 close to measured valued of 2.507

for K (1S)^2 (2S,2P)^8 (3S,3P)^8 (4S)^1
S= (10 x 1.0) + (8 x 0.85) = 16.8
Zeff = 19 - 16.8 = 2.2

Answer 2

For Na (1S)^2 (2S,2P)^8 (3S)^1
Zeff=Z-S S= (2 x 1.0) + (8 x0.85) = 8.8
Zeff = 11 - 8.8 = 2.2 close to measured valued of 2.507

for K (1S)^2 (2S,2P)^8 (3S,3P)^8 (4S)^1
S= (10 x 1.0) + (8 x 0.85) = 16.8
Zeff = 19 - 16.8 = 2.2 NOT close to measured value of 3.495 I don't know why K is so far off! Nor why both values come out to be 2.2
But by Slater's rules these are the estimates....

3. Yes, the second method accounts for the gradual increase in .