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Chemistry 1 > Chapter 11: Chemical Bonding II: Molecular Shapes, Valence Bond Theory, and Molecular Orbital Theory > Flashcards

Chapter 11: Chemical Bonding II: Molecular Shapes, Valence Bond Theory, and Molecular Orbital Theory Flashcards

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1
Q

Properties of molecular substances depend on what?

A

the structure of the molecule

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2
Q

what does the structure include?

A

The skeletal arrangement of the atoms
type of bonding between the atoms
The shape

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3
Q

allow us to predict the shapes of molecules

A

the bonding theories

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4
Q

have characteristic “corners” that indicate the positions of the surrounding atoms around a central atom in the center of the geometric figure.

A

geometric figures

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5
Q

The geometric figures also have characteristic angles that we call

A

bond angles

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6
Q

predicts there are distinct regions in an atom containing bonding and nonbonding electrons

A

Lewis

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7
Q

distinct regions in an atom containing bonding and nonbonding electrons

A

electron groups

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8
Q

repel each other as they are regions of negative charge

A

electron groups

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9
Q

what charges are electron groups

A

negative

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10
Q

can be used to predict the shapes of the molecules.

A

The repulsion of electron groups in Lewis structures

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11
Q

The position of atoms surrounding a central atom will be determined by what?

A

the location of the bonding electron groups.

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12
Q

are positioned to minimize repulsive forces.

A

the electron groups

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13
Q

what is the VSEPR theory

A

Electron groups around the central atom will be most stable when they are as far apart as possible.

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14
Q

what constitutes as a electron group on a central atom

A

Each lone pair of electrons
and
Each bond regardless of whether it is single, double, or triple

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15
Q

For molecules with a single central atom that exhibit what the electron geometry is the same for all structures

A

resonance

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16
Q

When there are two electron groups around the central atom, This results in the electron groups taking a

A

linear electron geometry.

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17
Q

What shape will this molecule make

A

Linear electron geometry

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18
Q

what is the bond angle for linear electron geometry.

A

180 degrees

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19
Q

When there are three electron groups around the central atom, This results in the electron groups taking a

A

trigonal planar electron geometry

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20
Q

What Shape will this molecule make?

A

Trigonal planar electron geometry

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21
Q

what bond angle is trigonal planar electron geometry

A

120 degrees

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22
Q

When there are four electron groups around the central atom, This results in the electron groups taking a

A

tetrahedral electron geometry.

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23
Q

What shape does this molecule take

A

Tetrahedral electron geometry

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24
Q

what is the bond angle for tetrahedral electron geometry.

A

109.5°

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25
Q

When there are five electron groups around the central atom, This results in the electron groups taking a

A

Trigonal Bipyramidal Electron Geometry

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26
Q

What shape does this molecule take

A

Trigonal Bipyramidal electron geometry

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27
Q

what are the two positions in Trigonal Bipyramidal Electron Geometry

A

axial

and

equatorial

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28
Q

what is the bond angle for equatorial positions

A

120 degrees

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29
Q

The bond angle between axial and equatorial positions is what?

A

90 degrees

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30
Q

The positions above and below the central atom are called the

A

axial positions

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31
Q

What shape does this molecule take

A

Ortahedral geometry

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32
Q

The positions in the same base plane as the central atom are called the

A

equatorial positions

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33
Q

When there are four electron groups around the central atom, This results in the electron groups taking a

A

Octahedral Electron Geometry

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34
Q

The actual geometry of the molecule is called its

A

molecular geometry

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35
Q

what affects molecular geometry?

A

groups attached to atoms of diff sizes and

binding to one atom is different form other atom

Lone pairs

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36
Q

“occupy more space” on the central atom because their electron density is exclusively on the central atom, rather than shared like bonding electron groups.

A

Lone pairs

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37
Q

Relative sizes of repulsive force interactions is as follows:

A

Lone Pair – Lone Pair > Lone Pair – Bonding Pair > Bonding Pair – Bonding Pair

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38
Q

The bonding electrons are shared by two atoms, so some of the what is removed from the central atom.

A

negative charge

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39
Q

The nonbonding electrons are localized on the central atom, so the area of negative charge what?

A

takes more space

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40
Q

When there are four electron groups around the central atom, and one is a lone pair, the result is called a

A

trigonal pyramidal molecular geometry,

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41
Q

What is this?

A

Trigonal pyramidal molecular geometry

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42
Q

what are the bond angles of trigonal pyramidal molecular geometry,

A

107 degrees

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43
Q

When there are four electron groups around the central atom, and two are lone pairs, the result is called a

A

tetrahedral–bent molecular geometry.

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44
Q

What is this

A

Tetrahedral-bent molecular geometry

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45
Q

what are the bond angles of tetrahedral–bent molecular geometry.

A

104.5

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46
Q

When there are three electron groups around the central atom, and one of them is a lone pair, the resulting shape of the molecule is called a

A

trigonal planar–bent molecular geometry.

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47
Q

What is this

A

Trigonal planar-bent molecular geometry

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48
Q

what is the bond angle of trigonal planar–bent molecular geometry?

A

less than 120°

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49
Q

What is this?

A

Seesaw shape or distorted tetrahedron

50
Q

When there are five electron groups around the central atom, and one is a lone pair, the result is called the

A

seesaw shape (aka distorted tetrahedron).

51
Q

What is this

A

T-shaped

52
Q

When there are five electron groups around the central atom, and two are lone pairs, the result is

A

T-shaped.

53
Q

What is this

A

Square Pyramidal Shape

54
Q

When there are six electron groups around the central atom, and one is a lone pair, the result is called a

A

square pyramid shape

55
Q

What is this

A

Square planar shape

56
Q

When there are six electron groups around the central atom, and two are lone pairs, the result is called a what

A

square planar shape.

57
Q

indicate bonds on the same plane with what?

A

straight line

58
Q

For atoms in front of the plane, use a

A

solid wedge

59
Q

For atoms behind the plane, use a

A

hashed wedge.

60
Q

The bonding electrons are pulled equally toward both O ends of the molecule. The net result is a what?

A

nonpolar molecule

61
Q

polarity depends on what?

A

the shape of the molecule

62
Q

Both sets of bonding electrons are pulled toward the O end of the molecule. The net result is a what?

A

polar molecule.

63
Q

affects the intermolecular forces of
attraction.

A

polarity

64
Q

which shapes are polar?

A

bent
and
trigonal pyramidal

65
Q

which shapes are non polar?

A

linear
trigonal planar
tetrahedral

66
Q

polar molecules are attracted to what?

A

other polar molecules

67
Q

do ionic compounds dissolve in water?

A

yes

68
Q

problems with the lewis model

A
  • does not give good numerical predictions.
  • cannot be used to get the actual angle.
  • Cannot write one correct structure for many molecules where resonance is important.
  • Often does not predict the correct magnetic behavior of molecules.
69
Q

The electron density of the valence electrons is localized between the bonding atoms.

A

Valence Bond (VB) Theory

70
Q

The valence electrons, located in half-filled atomic orbitals (s, p, d, and f), overlap to form molecular bonds.

A

Valence Bond (VB) Theory

71
Q

The electron density of the valence electrons is delocalized within the molecule.

A

Molecular Orbital (MO) Theory

72
Q

The valence electrons occupy molecular orbitals that spread throughout the entire molecule.

A

Molecular Orbital (MO) Theory

73
Q

When orbitals on atoms interact constructively, they make a bond.

A

valence bond theory

74
Q

If the energy of the system is lowered because of these interactions, a what forms?

A

chemical bond

75
Q

a chemical bond results from what according to the VB theory

A

from the overlap of two half- filled orbitals with spin-pairing of the two valence electrons

or

the overlap of a completely filled orbital with an empty orbital.

76
Q

what determines the shape of the molecule?

A

The geometry of the overlapping orbitals

77
Q

As two atoms approach each other, the half-filled valence atomic orbitals on each atom would interact to form

A

molecular orbitals

78
Q

are regions of high probability of finding the shared electrons in the molecule.

A

molecular orbitals

79
Q

The potential energy is lowered when?

A

the molecular orbitals contain a total of two paired electrons compared to separate, one-electron atomic orbitals.

80
Q

issues with the VB theory

A

does not predict the number of bonds or orientation of bonds.

81
Q

apparently, valence atomic orbital what before binding takes place

A

hybridize

82
Q

producing four hybrid orbitals that point at the corners of a tetrahedron.

A

hybridze

83
Q

involves the mixing of different types of orbitals in the valence shell to make a new set of degenerate orbitals.

A

Hybridization

84
Q

what determines the shape of a hybrid orbital?

A

The number and type of standard atomic orbitals

85
Q

The particular kind of hybridization that occurs is the one that what?

A

yields the lowest overall energy for the molecule

86
Q

For hybridization what are central atoms with four electron groups

A

sp3 hybridized

87
Q

what geometry does sp3 hybridized have?

A

Tetrahedral geometry

88
Q

On-axis overlap of atomic orbitals produce what?

A

sigma bonds

89
Q

Unhybridized p orbital can overlap adjacent to the internuclear axis with the unhybridized p orbital of another atom forming a

A

pi bond.

90
Q

where are sigma bonds usually seen

A

Either standard atomic orbitals or hybrids
s to s, p to p, hybrid to hybrid, s to hybrid, etc.

91
Q

results when the bonding atomic orbitals are parallel to each other and perpendicular to the axis connecting the two bonding nuclei.

A

pi bond

92
Q

which is stronger pi bonds or sigma bonds

A

sigma bonds

93
Q

“Overlap” between a hybrid orbital on one atom with a hybrid or non-hybridized orbital on another atom results in a what?

A

sigma bond

94
Q

“Overlap” between unhybridized p orbitals on bonded atoms results in a what?

A

pi bond

95
Q

rotation around what bond does not require breaking the interaction between the orbitals

A

sigma

96
Q

rotation around what bond does require breaking the interaction between the orbitals

A

pi

97
Q

which hybridization is four electron groups?

A

sp^3 hybridization

98
Q

which hybridization is three electron groups?

A

sp^2

99
Q

which geometry does sp^2 have?

A

trigonal planar system

100
Q

which hybridization is two electron groups?

A

sp hybridization

101
Q

what shape is sp hybridization?

A

linear

102
Q

which hybridization is five electron groups?

A

sp^3d

103
Q

what shapes are the sp^3d?

A

-Trigonal bipyramid
-Seesaw
-T–shape
-Linear

104
Q

which hybridization is six electron groups?

A

sp^3d^2

105
Q

what shapes are the sp^3d^2?

A
  • Octahedral electron
    -Square pyramid
    -Square planar
106
Q

limitations of the VB theory are

A

-doesn’t describe magnetic behavior of O2
-doesn’t account for delocaliztion

107
Q

in this theory we apply Schrödinger’s wave equation to the molecule to calculate a set of molecular orbitals.

A

Molecular Orbital (MO) Theory

108
Q

what is special ab the Molecular Orbital (MO) Theory

A

the electrons and orbital belong to the whole molecule

109
Q

The simplest mathematical solution is the summation of the atomic orbitals of the atoms to form molecular orbitals; this summation is called the

A

linear combination of atomic orbitals (LCAO)

110
Q

Because the orbitals are wave functions, the waves can combine either what or what?

A

constructively or destructively.

111
Q

this wave function results in a molecular orbital that has less energy than the original atomic orbitals

A

constructively

112
Q

what is a constructively wave called

A

bonding molecular orbital.

113
Q

where can most of the electron density be found in binding (MO)

A

between the nuclei

114
Q

this wave function results in a molecular orbital that has more energy than the original atomic orbitals

A

destructively

115
Q

where can most of the electron density be found in antibinding (MO)

A

outside the internuclear axis

116
Q

which has more energy electron in bonding MO or atomic orbitals

A

atomic orbitals

117
Q

which has more energy electron in antibonding MO or atomic orbitals

A

antibonding MO

118
Q

Electrons in antibonding orbitals what stability gained by electrons in bonding orbitals.

A

cancel

119
Q

if there are unpaired electrons what is the substance?

A

paramagnetic

120
Q

if there are no unpaired electrons what is the substance?

A

diamagnetic

121
Q

When the combining atomic orbitals
are of different types and energies, which orbital contributes more to the molecular orbital.

A

the atomic orbital closest in energy to the molecular orbital

122
Q

When many atoms are combined together, the atomic orbitals of all the atoms are combined to make a set of molecular orbitals, which are

A

delocalized over the entire molecule.

Chemistry 1 (14 decks)

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