L07 Chem 111A Lecture Notes - Lecture 24: Effective Nuclear Charge, Periodic Trends, Potential Energy

• School: WUSTL
• Department: University College - Chemistry
• Course: L07 Chem 111A
• Professor: Buhro William

Document Summary

Core electrons screen valence electrons which therefore experience a lesser z* The 3s orbital penetrates the core because of its secondary maxima and thus t a greater z* then do the 3p and 3d orbitals. The 3p in turn penetrates the core more than the 3d does. Because of these relationships the z* ns > z* np > z* nd > z* nf, i. e. effective nuclear charge increases across a period. To see the relationship between energy and the orbitals (why orbitals of the same quantum number n have different energy), look at the potential energy equation: (cid:1848)= (cid:2910) (cid:3032)(cid:3118)(cid:3080)(cid:3045) Potential energy is inversely related to r and directly related to z* As z* increases or r decreases orbital energy decreases and the etot of the orbital decreases therefore ens < enp < end < end for multi electron atoms/ions. Graph of z* on outermost e- over the first 2 rows of the periodic table.