Molecular Orbital Theory (ch. 10.8) Flashcards
Define molecular orbital (MO) theory
???
Molecular orbitals with the lowest energy area the ____ approximations of the actual molecular orbitals
Best
What does LCAO stand for?
Linear combinations of atomic orbitals
The Ō1s orbital is _____ in energy than than either of the the two 1s orbitals from which it was formed
Lower
Define bonding orbital
????
When electrons occupy bond molecular orbitals, the energy of the electrons is lower than it would be if they were occupying _____ _____
Atomic orbitals
Define antibonding orbital
???
e- in antibonding orbitals have ____ energies than they did in their respective atomic orbitals and therefore it tends to ____ the energy of the system
Higher raise (increase)
In general when two atomic orbitals are added together to form molecular orbitals, one of the resultant molecular orbitals will be _____ in energy (bonding orbital) than the atomic orbitals, and the other will be ____ in energy (antibonding orbital)
Lower
Higher
Bonding orbitals are the result of _____ interference
Constructive
Anti bonding orbitals are the result of _____ interference
Destructive
A bonding orbital has an _____ electron density in the internuclear region
Increased
An antibonding orbital has an _____ electron density in the internuclear region
Zero (a node occurs)
Why do bonding orbitals have a lower energy energy compared to orbitals of nonbonded atoms?
Because there is s greater electron density in the internuclear region
Antibonding orbitals generally have higher energies than orbitals of nonbonded atoms because…
Antibonding orbitals have less electron density in the internuclear region
Bond order = …
{(# of e- in bonding MOs) -(# of e- in antibonding MOs)} /2
What does a positive bond order mean?
There are more electrons in bonding orbitals than antibonding orbitals
In general, the higher the bond order, the _____ the bond
Stronger
A negative or zero bond order indicates that…?
The bond will not form between the atoms
The total number of MOs formed from a particular set of AOs will always equal…?
The umber of AOs In the set
What is the difference between valence bond theory and molecular orbital theory?
Valence bond treats e- as if they reside in quantum mechanical orbitals calculated for ATOMS (this is partially compensated for by hybridization but not enough)
Molecular orbital theory has e- residing in molecular orbitals
