Ch 5: Bonding and Intermolecular Forces

Question 1

Why aren’t electrons in d subshells considered valence electrons for transition metals?

Answer 1

Because valence electrons are in the highest n level, and the d subshell “goes back” one n level.

p. 90

Question 2

The ideal Lewis structures satisfies the octet rule for all atoms and has a formal charge of zero on all the atoms.

If this is not possible then the best structure is the one that _________ the _________ of the formal charges.

Answer 2

minimizes

magnitudes

p. 92

Question 3

For dot structures that must contain formal charges on one or more atoms, the best structures have ________ formal charges on the more ______________ element.

Answer 3

negative

electronegative

p. 92

Question 4

When multiple dot structures seem possible, which atom should be chosen as the central atom?

Answer 4

the least electronegative atom

p. 93

Question 5

Resonance structures are two or more structure where only _________ electrons, as well as ______ and ______ bonds may move around.

Answer 5

nonbonding

double

triple

p. 95

Question 6

What is the one rule of VSEPR theory?

Answer 6

Since electrons repel one another, electron pairs, whether bonding or nonbonding, attempt to move as far apart as possible.

p. 99

Question 7

What is bond dissociation energy?

Answer 7

the energy required to break a bond homolytically

p. 95

Question 8

What does “homolytically” mean?

Answer 8

This refers to homolytic bond cleavage (or dissociation) where one electron of the bond being broken goes to each fragment of the molecule.

p. 95

Question 9

Homolytic bond cleavage differs from HETEROLYTIC bond cleavage where both electrons of the bond being broken end up on the ____ ____, forming both a ______ and an _____.

Answer 9

same atom

cation, anion

p. 95

Question 10

Hint: When you think of bond dissociation energy, think of a divorce in which each partner got an equal share of the assets. The “assets” in this case are _________.

Answer 10

electrons

Question 11

The bond order is defined as…

Answer 11

…the number of bonds between adjacent atoms.

p. 95

Question 12

The higher the bond order, the….

Answer 12

….shorter and stronger the bond.

p. 95

Question 13

Bond lengths are often reported in angstrom. What is an angstrom?

What unit are bond dissociation energies given in?

Answer 13

10^-10 m

kcal/mol

p. 95

Question 14

Because of varying ______ _____, bond length and bond dissociation energy comparisons should be made for similar bonds (i.e. C-C bonds compared to other C-C bonds; C-O bonds compared to other C-O bonds)

Answer 14

atomic radii

p. 96

Question 15

When comparing the same type of bonds, the greater the s character in the hybrid orbitals, the shorter the bond. Why is this?

Answer 15

because s-orbitals are closer to the nucleus than p-orbitals due to their shape. S-orbitals are spheres and p-orbitals have that dumbbell shape.

Example: an sp-sp bond will be shorter than an sp-sp³ bond

In other words, the fewer p’s involved, the shorter the bond will be.

p. 96

Question 16

A sigma bond consists of 2 electrons that are _________ between 2 nuclei, formed by end-to-end overlap of orbitals from each of the 2 atoms participating in the bond.

Answer 16

localized

p. 104

Question 17

A pi bond is composed of 2 electrons that are localized to the region that lies on each side of the plane formed by the ___ ______ ______ and immediately adjacent atoms, not directly between the two nuclei as with a sigma bond.

Answer 17

two bonded nuclei

Question 18

In any multiple bond, there is only _ sigma bond, the remainder are __ bonds.

Answer 18

1

pi

p. 106

Question 19

Name the electron and molecular geometry for a molecule with the following AXE classification:

AX₂E₀

Answer 19

Bc there are no lone pairs, they will both have linear geometry. (bond angle 180 degrees)

Question 20

Name the electron and molecular geometry for a molecule with the following AXE classification:

AX₃E₀

Answer 20

Bc there are no lone pairs, they will both have trigonal planar geometry. (bond angle 120 degrees)

Question 21

Name the electron and molecular geometry for a molecule with the following AXE classification:

AX₂E₁

Answer 21

electron geometry will be trigonal planar, molecular geometry will be bent. (bond angle <120 degrees)

Question 22

Name the electron and molecular geometry for a molecule with the following AXE classification:

AX₄E₀

Answer 22

Bc there are no lone pairs, they will both have tetrahedral geometry (bond angle 109.5)

Question 23

Name the electron and molecular geometry for a molecule with the following AXE classification:

AX₃E₁

Answer 23

Electron geometry will be tetrahedral, molecular geometry will be trigonal pyramidal. (bond angle <109.5, ~107)

Question 24

Name the electron and molecular geometry for a molecule with the following AXE classification:

AX₂E₂

Answer 24

Electron geometry will be tetrahedral, molecular geometry will be bent. (Bond angle will be < 109.5, ~105)

Question 25

Name the electron and molecular geometry for a molecule with the following AXE classification:

AX₅E₀

Answer 25

Bc there are no lone pairs, they will both have trigonal bipyramidal geometry. (bond angles 90 and 120)

Question 26

Name the electron and molecular geometry for a molecule with the following AXE classification:

AX₄E₁

Answer 26

Electron geometry will be trigonal bipyramidal, molecular geometry will be see-saw (bond angles <90, and <120)

Question 27

Name the electron and molecular geometry for a molecule with the following AXE classification:

AX₃E₂

Answer 27

Electron geometry will be trigonal bipyramidal, molecular geometry will be a T-structure. (bond angle <90)

Question 28

Name the electron and molecular geometry for a molecule with the following AXE classification:

AX₂E₃

Answer 28

Electron geometry will be trigonal bipyramidal.

Molecular geometry will be linear. (Bond angle 180).

Question 29

Name the electron and molecular geometry for a molecule with the following AXE classification:

AX₆E₀

Answer 29

Bc there are no lone pairs, they will both have octahedral geometry. (Bond angles 90 and 90).

Question 30

Name the electron and molecular geometry for a molecule with the following AXE classification:

AX₅E₁

Answer 30

Electron geometry will be octahedral.

Molecular geometry will be square pyramidal. (Bond angles 90 and <90).

Question 31

Name the electron and molecular geometry for a molecule with the following AXE classification:

AX₄E₂

Answer 31

Electron geometry will be octahedral.

Molecular geometry will be square planar. (Bond angles all 90).