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Hund’s rule: The lowest energy state of an atom is achieved when there is maximum utilization of the surrounding space by the occupying electrons. Pairing of electrons in an orbital is recognized as a higher energy state than single electrons of the same spin state occupying the orbitals. This does not apply to s orbitals.
Pauli exclusion principle: No two electrons in an atomic orbital may share the same set of quantum numbers. This rule led to the realization that electrons in the same orbital must be of opposite spins.
Two Major Rules in Chemical Physics that impinge on the behavior of minerals
2s
X
Y
Z
1s
2px
2px 2py 2py
2pz
2pz
3s
1s 2s, 2p
n= n= n=3 3s, 3p, 3d
2s
(K shell) (L shell) (M shell)
Quant No. (^) Configuration.
2 p orbitals. At the second quantum level orientation also becomes a factor in deciding orbital energy. Because there are 3 orientations existing simultaneously, a p orbital can hold a maximum of 6 electrons, 2 of opposite spin in each
Shapes are the same, but differ in orientation
Element (At. No.)
Ground-state configuration
Abbreviated form
Sodium (11) 1 s^22 s^22 p^63 s^1 [Ne]3 s^1
Magnesium (12) 1 s^22 s^22 p^63 s^2 [Ne]3 s^2
Aluminum (13) 1 s^22 s^22 p^63 s^23 p^1 [Ne]3 s^23 p^1
Silicon (14) 1 s^22 s^22 p^63 s^23 p^2 [Ne]3 s^23 p^2
Phosphorus (15) 1 s^22 s^22 p^63 s^23 p^3 [Ne]3 s^23 p^3
Sulfur (16) 1 s^22 s^22 p^63 s^23 p^4 [Ne]3 s^23 p^4
Chlorine (17) 1 s^22 s^22 p^63 s^23 p^5 [Ne]3 s^23 p^5
Argon (18) 1 s^22 s^22 p^63 s^23 p^6 [Ne]3 s^23 p^6
Caution:
The 4 s orbital is actually at a lower energy level than the 3 d. As a result 4 s orbitals will fill before 3 d. But, when ionized, electrons will be lost from the 4 s before the 3 d
K = 1 s 2 s 2 p 3 s 3 p 3 d 4 s
Ca = 1 s^2 2 s^2 2 p^6 3 s^2 3 p^6 3 d 4 s^2
Solution: When n = 3, the atom must contain s, p, and d subshells and 3 energy states. But, recall that the 4s subshell with 2 electrons is of a lower energy state than the 3d subshell and will fill first
The most stable form occurs when both metals lose their 4s electrons. Thus:
K+^ and Ca2+
[Ar]4 s^1 and [Ar]4 s^2
Z = 19
Z = 20
First transition series
Macrominerals
Microminerals
3 d
4 d
5 d
1. Why do Ca2+^ , Mg 2+^ , and Zn2+^ exist only as +2 ions? Li+^ , Na +^ and K+^ as +1 ions?
- Ca = [Ar] 4s
- Mg = [Ne] 3s
- Zn = [Ar] 3d 10 4s - Li = [He] 2s
- Na = [Ne] 3s
Fe element No. 26
1 s^2 2 s^2 2 p^6 3 s^2 3 p^6 4 s^2 3 d^6
Z Z
Z Z
Z
X
X
X
X
Y^ Y^ X Y
Y Y
dxy
d yz
dxz
d X 2 -Y 2 dZ^2
