Question

Detailed calculations show that the value of Zefffor the outermost electrons in Na and K atoms is 2.51+ and 3.49+ , respectively.

Predict Zeff for the outermost electrons in the Rbatom based on the calculations for Na and K using Slater's rules.

Answer 1

Slater Rules is used for the evaluation of S=shielding constant

Zeff=Z-S

Where Zeff=effective nuclear charge

Z=actual nuclear charge

For electrons in valence s or p orbital. Slater rules states that [say ns or np valence orbital]

Grouping of orbitals to be done as orbitals in the same level have similar contributions to S

Grouping

(1s) ,(2s,2p),(3s,3p),(3d),(4s,4p),(4d,4f),(5s)….

1) electrons within the same group (ns,np) shields 0.35, (except 1s with shielding constant value of 0.30)

2)Electrons in (n-1)th group shields by 0.85

3)electrons in (n-2)th group shields by 1.00 each

For Rb atomic no=37

Z=37

Electron configuration=1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 5s1

(1s) ^2 ,(2s,2p)^8,(3s,3p)^8, (3d)^10 ,(4s,4p)^8,(4d,4f)0,(5s)^1….

S [5s1] =(1.00*28) + (8*0.85)=28.0+6.8=34.8

Zeff=Z-S=37-34.8=2.2