Slater's rules

Slater's Rules are a set of rules devised by John C. Slater that give an approximate estimate of effective nuclear charge on an electron (Z*).

$Z*=Z-S$

where S is the screening constant.

The system involves the two following steps:

1.Arrange sets according to principle quantum number, ignoring filling order and keeping ns and np together

i.e [1s] [2s,2p] [3s,3p] [3d] [4s,4p] [4d] [4f]

2.Using the table, calculate the contributions to S (the screening constant) for electrons in each set.

Set	Electrons in Higher Sets	Remaining Electrons in Same set	All electrons in lower sets	Electrons in set(s) with quantum number n-1	Electrons in all sets with quantum number <n-1
[1s]	0	0.3	N/A	N/A	N/A
[ns,np]	0	0.35		0.85	1
[nd] or [nf]	0	0.35	1