Aufbau Principle

Noah_CCN

为什么magnesium和aluminium成为Aufbau Principle的exception?

为什么4s1 3d5 比 4s2 3d4 更stable?

为什么4s1 3d10比 4s2 3d9 更stable?

是不是因为假如4s 的sub shell 只有一个electron的话没有repulsion而变得stable?

[ 本帖最后由 Noah_CCN 于 5-2-2006 01:10 PM 编辑 ]

Tenchi

这个能帮到你吗？

http://www.src.wits.ac.za/pages/ ... ture_03/node19.html

http://depts.washington.edu/chem ... dout_Lecture_19.pdf

Tenchi

Many elements, such as chromium has electronic states that are not at a
much higher state than the ground state. In the presence of other atoms
electrons are "promoted" to these low energy states favorably because the
energy gained in forming bonds exceeds the energy "cost" of "promoting" one
or more electrons. Carbon is the classic example: Its ground state
electronic configuration with its 6 electrons is: 1S2, 2S2, 2P.
From this one would "expect" carbon to have an oxidation state of 2, which
of course in seldom if ever does.
     In the case of Cr the energy levels of its outer shell are: 3D5, 4S1 ( 0
cm^-1); 3d5, 4S1 (7593 cm^-1). This is due to the more stable anti parallel
and less stable parallel spin orientation of the S and D electrons.
The next energy level has a configuration 3D4, 4S2 which involves 4 sub
energy levels centered at about (8000 cm^-1). This results in a multitude of
possible bonding states accessible to Cr. You can find the energy levels of
a lot of atoms and ions at the NIST web site: http://physics.nist.gov Look for
energy levels of atoms on that home page.