Older content exam 2 review Flashcards
What is “linear combination of atomic orbitals”?
each molecular orbital is constructed from a superposition of atomic orbitals
Why are some diatomic molecules not energetically favorable to form?
The difference in energy between the bonding and antibonding orbitals are asymmetrical
Wavefunctions _____ be either symmetric or antisymmetric around the molecules’ center of symmetry
MUST
What orbitals overlap to form energy bands? Which orbitals overlap first?
atomic, outer
What is the fermi energy?
the energy level of the maximum filled orbital at 0K
What is the work function?
difference between the fermi level and vacuum
______ orbitals can’t change without excitation with constant potential, _______ orbitals can
atomic, molecular
Why are orbitals in Si oriented to the four corners of a tetrahedral?
to minimize electron repulsion
Is the energy gap a physical space?
no, the band gap doesn’t have a physical location
If we decrease R in Si, what happens to the energy band?
it gets bigger
Does a bigger or smaller effective mass give a greater conductivity?
a smaller effective mass
What is the band gap?
energy difference between CB and VB
At 0K, are there any electrons in the CB?
no, they’re all in the VB
What is the density of states between n=3 and n=4?
2
What’s the density of states at n=1?
1
What happens to a metal with a lower fermi energy?
The number of electrons in the valence band increases
What is electrical work (eV) after combining metals?
the difference in the metals wavefunctions
What is the Pauli exclusion principle?
no two electrons can have the same set of quantum numbers
When two metals are brought together the Fermi energy level ______
aligns
Bohr approximation is used to approximate if the electron is _____ _______
spatially delocalized
In order for appreciable transport, we need _____ _____
spacially delocalized charge carriers
The energy levels that donor electrons fill are a function of
- # of donors
- donor orbital energies
- CB edge
If a band is full of electrons, those electrons ____ contribute to conduction
don’t
Any _____ bands can contribute to conduction
unfilled
Do electrons have the same effective mass in 3p and 4s bands?
no, their acceleration is different
