Chapter 7: Theories of Chemical Bonding

Question 1

Localized bonding

Answer 1

Electrons are localized in the bonds between two atoms, usually in pairs

Question 2

Delocalized bonding

Answer 2

Bonds delocalized over several atoms, which explains some chemical properties

Question 3

Orbital overlap

Answer 3

The addition of wave orbitals, generating a new orbital with high electron density between the nuclei

Question 4

What type of overlap do diatomic molecules have? HF

Answer 4

1s-2p overlap

Question 5

What type of overlap do diatomic molecules have? F2

Answer 5

2p-2p overlap

Question 6

What is the overlap in H2S?

Answer 6

1s-3p overlap

Question 7

Atomic orbitals can be hybridized to generate______. These mixed orbitals match the __________. All electrons around _________ must be in orbitals.

Answer 7

A new set of directional orbitals
Orbital geometry of the compounds
The central atom

Question 8

Hybridization

Answer 8

Combining atomic orbitals on a particular atom to form a special set of directional orbitals

Question 9

sp3 hybrid orbitals = ________ molecular geometry

Answer 9

Tetrahedral

Question 10

The ______ of an inner atom determines the number and type of hybrid orbitals

Answer 10

Steric number

Question 11

Do hybrid orbitals form localized or delocalized bonds with atomic orbitals/other hybrid orbitals?

Answer 11

Localized

Question 12

Are outer atoms hybridized?

Answer 12

No

Question 13

sp2 hybrid orbitals = _______ geometry

Answer 13

Trigonal planar (steric number 3)

Question 14

sp hybrid orbitals = ________ geometry

Answer 14

Linear (steric number 2)

Question 15

sp3d hybrid orbitals = _______ geometry

Answer 15

Trigonal bipyramidal (steric number 5)

Question 16

sp3d2 hybrid orbitals = __________ geometry

Answer 16

Octahedral (steric number 6)

Question 17

Double bond

Answer 17

Has two sets of bonding electrons and requires two sets of overlapping orbitals

Question 18

Triple bond

Answer 18

Has three sets of bonding electrons and requires three sets of overlapping orbitals

Question 19

A single overlap of two orbitals is called______?

Answer 19

A sigma bond (electron density is distributed along the axis)

Question 20

A double overlap of two orbitals is called________?

Answer 20

A pi bond (electrons density is distributed above and below the bond axis)

Question 21

Why does silicon form weak pi bonds?

Answer 21

The 3p orbitals are too far apart for strong side-by-side overlap

Question 22

What type of bonds are triple bonds?

Answer 22

One sigma bond and 2 pi bonds

Question 23

How can bonding in diatomic molecules second row elements be explained?

Answer 23

1. Localized bonding
2. Pure s and p atomic orbitals that combine to produce orbitals that are delocalized over several atoms leading to molecular orbitals

Question 24

What are the advantages of molecular orbitals over localized bonding theory?

Answer 24

1. You can predict relative bond lengths and energies
2. Predict magnetic properties
3. Correctly explain electronic structures of molecules that do not follow lewis dot structure

Question 25

What is the first principle of MO theory?

Answer 25

The total number of molecular orbitals produced by a set of interacting atomic orbitals is always equal to the number of interacting atomic orbitals

Question 26

What does adding orbitals =?

Answer 26

Bonding molecular orbitals

Question 27

What does subtracting orbitals =?

Answer 27

Anti-bonding molecular orbitals

Question 28

What is the second principle of MO theory?

Answer 28

The bonding molecular orbital is lower in energy than the parent orbitals and the anti-bonding orbital is higher in energy

Question 29

The system is _______when electrons are assigned to the bonding orbitals

Answer 29

Stabilized

Question 30

The system is ________when electrons are assigned to the anti-bonding orbitals because the energy of the system is higher

Answer 30

Destabilized

Question 31

How do you calculate bond order?

Answer 31

1/2 (#electrons in bonding MOs-#electrons in anti-bonding MOs)

Question 31

What is the third principle of MO theory?

Answer 31

Electrons of the molecule are assigned to orbitals based on the aufbau principle and Hund’s rule

Question 32

A bond order of 1 represents____?

Answer 32

A single bond

Question 33

What does a bond order of 1.5 indicate?

Answer 33

A bond that is intermediate between a single and double bond