Molecular Orbital Theory (ch. 10.8)

Question 1

Define molecular orbital (MO) theory

Answer 1

???

Question 2

Molecular orbitals with the lowest energy area the ____ approximations of the actual molecular orbitals

Answer 2

Best

Question 3

What does LCAO stand for?

Answer 3

Linear combinations of atomic orbitals

Question 4

The Ō1s orbital is _____ in energy than than either of the the two 1s orbitals from which it was formed

Answer 4

Lower

Question 5

Define bonding orbital

Answer 5

????

Question 6

When electrons occupy bond molecular orbitals, the energy of the electrons is lower than it would be if they were occupying _____ _____

Answer 6

Atomic orbitals

Question 7

Define antibonding orbital

Answer 7

???

Question 8

e- in antibonding orbitals have ____ energies than they did in their respective atomic orbitals and therefore it tends to ____ the energy of the system

Answer 8

Higher 
raise (increase)

Question 9

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)

Answer 9

Lower

Higher

Question 10

Bonding orbitals are the result of _____ interference

Answer 10

Constructive

Question 11

Anti bonding orbitals are the result of _____ interference

Answer 11

Destructive

Question 12

A bonding orbital has an _____ electron density in the internuclear region

Answer 12

Increased

Question 13

An antibonding orbital has an _____ electron density in the internuclear region

Answer 13

Zero (a node occurs)

Question 14

Why do bonding orbitals have a lower energy energy compared to orbitals of nonbonded atoms?

Answer 14

Because there is s greater electron density in the internuclear region

Question 15

Antibonding orbitals generally have higher energies than orbitals of nonbonded atoms because…

Answer 15

Antibonding orbitals have less electron density in the internuclear region

Question 16

Bond order = …

Answer 16

{(# of e- in bonding MOs) -(# of e- in antibonding MOs)} /2

Question 17

What does a positive bond order mean?

Answer 17

There are more electrons in bonding orbitals than antibonding orbitals

Question 18

In general, the higher the bond order, the _____ the bond

Answer 18

Stronger

Question 19

A negative or zero bond order indicates that…?

Answer 19

The bond will not form between the atoms

Question 20

The total number of MOs formed from a particular set of AOs will always equal…?

Answer 20

The umber of AOs In the set

Question 21

What is the difference between valence bond theory and molecular orbital theory?

Answer 21

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