CHEM Midterm #1 Flashcards
What is a planar node?
horizontal node
What is a radial node?
vertical node
Define degenerate orbitals
orbitals that have the same energy
What are the rules for filling MOs and AOs
- start by filling the lowest energy orbital first
- only two electrons can occupy an orbital
- apply Hund’s rule for filling degenerate MOs
What is Hund’s rule?
every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied
What is the bond order formula?
1/2 (number of electrons in bonding orbitals - number of electrons in antibonding orbitals)
How do you calculate orbital energy?
electron kinetic energy + electron-nuclear attraction + electron-electron repulsion
How is a sigma bonding orbital created?
Adding orbitals in the same phase
How is a sigma antibonding orbital created?
Subtracting orbitals (adding orbitals in 2 different phases)
Define constructive interference
when two waves superimpose and the resulting wave has a higher amplitude than the previous waves
Define destructive interference
when two waves superimpose and cancel each other out, leading to a lower amplitude
Define superimpose
The ability for an object to be placed over another object
In an MO diagram, which orbitals are bonding, antibonding, and non-bonding?
Bonding = lower in energy than the atomic orbitals
Antibonding = higher in energy than the AOs
Non-bonding = same energy as the AOs
How many MOs will exist per AO?
There are the same number of MOs as AOs
Which bond order causes the bond to break?
0
What does out phase and in phase mean?
out phase = 2 orbitals that are in different phases
in phase = 2 orbitals that are in the same phase
Define orthogonal
perpendicular to
What does a pi-bond look like?
Has a nodal plane through the bond axis
When can 2s orbitals combine with 2p orbitals?
when the orbitals are close enough in energy (within +/- 1 Ry = 2.179x10^-18 J = RH)
What is a parallel spin?
Multiple electrons in same direction