Question

what is z effective of last electron of scandium (Z=21)

Answer 1

z is a atomic no

last electron of scandium is 3

Answer 2

Answer:3

Explanation:The electronic configuration of scandium (z=21) is

(1s2) (2s2 2p6) (3s2 3p6) (3d1) (4s2)

Now according to Slater's rule for 's' electrons

1. Electrons in the same shell shield 0.35 each. Except 1s

2. All electrons in the (n -1) shell shield 0.85 each.

3. All electrons in(n-2) or lower group shield completely that is 1.00 each

I will represent '¶' as shielding constant.

¶ = 1×0.35 + 9×0.85 + 10×1

¶ = 18

Z eff = Z-¶

Z eff = 21 -18

Zeff = 3