Previously Auf Bau buildup was used to construct electron
configurations such as 1s22s22p6 (neon). Here you
see an energy diagram.
Hund's Rule- "Degenerate orbitals fill up in a way to maximize
the number of orbitals ocupied by electrons with the same spin.
If two or more orbitals have the same energy, we say that they
are degenerate.
A set of 'p' orbitals (all three) are degenerate.
A set of 'd' orbitals (all five) are degenerate.
We haven't discussed "spin". If the arrow points up, the
electron has one type of spin. If the arrow points down,
the electron has the opposite type of spin. Only two types
of spin are possible.
Pauli Exclusion Principle- An orbital may contain a maximum of two electrons.
Notice also that for each orbital, one arrow points up, and the other points down. It would be incorrect to fill an orbital with two arrows pointing up, or two arrows pointing down.
Return to Master Alchemist Index