E-Storeslaters rules for calculating screening effect
24 Jun 2007 22:17:04 IST
slaters rules for calculating screening effect
J.C.Slater prposed an empirical constant that represents the extent to wwhich the other electrons of the atom shield ( or screen ) any particular electron from the nuclear charge . thus slaters screening constant is used in the following equation :
Z* = Z - sigma
here , Z is the atomic number of the atom , and hence is equal to the actual number of the protons in the atom . the parameter Z* is the effctive nuclear charge , which according to the above equation is smaller that Z , since the electron n the question is screened ( shielded ) frm Z by an amount sigma . we found that for cases in which the screening is small , the effective nuclear charge is large . conversely , an electron that is well shielded ( large value for sigma in the above equation ) from the nuclear charge Z experiences small effective nuclear charge Z* .
the value for sigma for any one electron in the given eectronic configuration ( i.e in the presence of other electrons of the atom in the question ) is calculated using a set of empirical rules developed by slater . according to these rules , the value of sigma for the electron in question is the cumulative total provided by the various other electrons of the atom . the other electrns of the atom add an intrinsically different contribution to the value of s as follows :
if the electron in the question resides in a s or a p orbital
1. all electrons in the principle shell higher than the electron n the question contribute zero to sigma .
2. each electron ion the same shell contributed 0.35 to sigma
3. electrons in the (n-1) shell each contribute 0.85 to sigma .
4. electrons n the deeper shel contribute 1 to sigma .
if the electron in the queston resides in a d or f orbital
1. all electrons in principle shell higher than theelectron in question contribute zero to sigma
2. each electrn in the same principle shell contribute 0.35 to sigma .
3. all inner shell electrons ( i.e. (n-1) and lower ) uniformly contribute 1 to sigma .
Comments (1)
Free Sign Up!
Preparing for IIT-JEE ?
Arihant Revision Package for IIT JEE - Books, Practice Tests + Rank Predictor
@ INR 1,995/-
For Quick Info
|
|
|
|
|
| 35,229,755 Engineering Questions Attempted |
6,69,530 Visitors Monthly |
79 Engg. Exam Covered |
2096 Students Currently Online |
Connect with Us  |
 |
Vriti Communities
Privacy Policy © Vriti 2011
You have done quite well in explaining this phenomenon
Liked it a lot !
Keep up the good work !