3. Bonding, Structure & Energy Changes Flashcards

1
Q

describe e-s in a covalent bond

A

shared between 2 atoms

attracted to both nuclei simultaneously

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2
Q

describe e-s in a non polar bond

A

e- attracted to both nuclei same extent = forms symmetrical e- cloud

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3
Q

between what molecules/atoms do non polar bonds form

A

betw non metal atoms of same kind

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4
Q

describe e-s in a polar covalent bond

A

e shared unevenly between atoms

unsymmetrical e- cloud

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5
Q

for a tetrahedral how many bonded and non bonded e- pairs are there and what is the angle

A

4 bond
0 lone

109.5*

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6
Q

for a trigonal pyramid how many bonded and non bonded e- pairs are there and what is the angle

A

3 bond
1 lone

109.5*

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7
Q

for a v shaped how many bonded and non bonded e- pairs are there and what is the angle

A

2 bond
2 lone

109.5

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8
Q

for a trigonal planar how many bonded and non bonded e- pairs are there and what is the angle

A

3 bond
0 lone

120

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9
Q

for a v shaped how many bonded and non bonded e- pairs are there and what is the angle

A

2 bond
1 lone

120

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10
Q

for a linear how many bonded and non bonded e- pairs are there and what is the angle

A

2 bond
0 lone

180

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11
Q

for a trigonal bipyramidal how many bonded and non bonded e- pairs are there and what is the angle

A

5 bond
0 lone

120 & 90

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12
Q

for a distorted tetrahedron or seesaw how many bonded and non bonded e- pairs are there and what is the angle

A

4 bond
1 lone

120 & 90

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13
Q

for a T shaped how many bonded and non bonded e- pairs are there and what is the angle

A

3 bond
2 lone

90

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14
Q

for a octahedral how many bonded and non bonded e- pairs are there and what is the angle

A

6 bond
0 lone

90

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15
Q

for a square pyramid how many bonded and non bonded e- pairs are there and what is the angle

A

5 bond
1 lone

90

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16
Q

for a square planar how many bonded and non bonded e- pairs are there and what is the angle

A

4 bond
2 lone

90

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17
Q

how many orbitals does s sub level have

A

1

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18
Q

how many orbitals does p sub level have

A

3

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19
Q

how many orbitals does d sub level have

A

5

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20
Q

how many orbitals does f sub level have

A

7

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21
Q

what is different about orbital levels for transitional elements

A

4s level overlaps between 3p and 3d levels

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22
Q

1st energy level has how many orbitals and how are these arranged

A

1 orbital

1s

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23
Q

2nd energy level has how many orbitals and how are these arranged

A

4 orbitals

2s + 3 x 2p

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24
Q

3rd energy level has how many orbitals and how are these arranged

A

9 orbitals

3s + 3 x 3p + 5 x 3d

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25
Q

4th energy level has how many orbitals and how are these arranged

A

16 orbitals

4s + 3 x 4p + 5 x 4d + 7 x 4f

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26
Q

what is the periodic table trend for size of atoms across period from left to right

A

decrease radii

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27
Q

explain why the size of atoms decreases across period from left to right

A

e- add to same energy level and proton add to nucleus

leads to increase nuclear charge

increase attraction between valence e- and nucleus = e- pulled closer to nucleus

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28
Q

what is the periodic table trend for size of atoms down a group

A

increase radii

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29
Q

explain why the size of atoms increase down a group

A

valence e- in higher energy level so e- further from nucleus

increased nuclear charge cant overcome increased distance from nucleus

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30
Q

what is the periodic table trend for size of + ion compared to the atom

A

smaller radii than atom

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31
Q

explain why the size of + ion is smaller compared to the atom

A

e- loss = loss of complete energy level so outer e- closer to the nucleus

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32
Q

what is the periodic table trend for size of - ion compared to the atom

A

larger radii

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33
Q

explain why the size of - ion is larger compared to the atom

A

e- added to valence shell = increase repulsions between e-

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34
Q

what is the periodic table trend for ionization energy across period from left to right

A

increases

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35
Q

explain why the ionization energy increases across period from left to right

A

increased nuclear charge and same energy level filled with e- across period so increase attraction to nucleus and valence -

decrease atomic radii so harder to remove valence e-

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36
Q

what is the periodic table trend for ionization energy down a group

A

decreases

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37
Q

explain why the ionization energy decreases down a group

A

increased distance between nucleus and valence e-

decreases attraction so less energy to remove valence e-

valence e- also repelled by other e- so valence e- shielded from nuclear attraction

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38
Q

what is the periodic table trend for electronegativity across a period from left to right

A

increase

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39
Q

what is the periodic table trend for electronegativity down a group

A

decrease

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40
Q

explain why the electronegativity decreases down a group

A

valence e- further from nucleus and shield from other e-

decrease attraction of bonding e- and nucleus

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41
Q

explain why the electronegativity increases across a period from left to right

A

increase nuclear charge increases attractive nucleus and valence e-

increases attractive bond e- and nucleus

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42
Q

what forces hold together molecular substances

A

van der waals

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43
Q

what kind of dipoles are between non polar molecules and polar molecules respectively

A

betw non polar molecules = temporary diploe

betw polar molecules = permanent dipole

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44
Q

for molecular substances

what is the melt/boiling point relatively speaking and why

A

low

due to weak van der waal forces

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45
Q

for molecular substances

what is the electricity conduction and why

A

none

no charged particles

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46
Q

for molecular substances

what is the solubility in water and why

A

low

solvent water and solute intermolecular forces are of different magnitudes

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47
Q

for molecular substances

what is the solubility in non polar solvents and why

A

solube

same kind/strength of solvent and solute intermolecular forces

48
Q

what are the 3 kinds of extended networks

A

ionic

covalent

metallic

49
Q

for ionic substances what arrangement are the bonds in and what kind of bonds are present

A

arranged in lattice bond with strong ionic bond

50
Q

for ionic substances

what is the melting/boiling points relatively speaking and why

A

high

strong ionic bonds

51
Q

for ionic substances

what is the conductivity and why

A

conductive only in liquid state

freely moving ions in soln

52
Q

for ionic substances

what is the solubility in polar solvents and why

A

soluble

solvent and solute attraction > attraction between ions

53
Q

for ionic substances

what is the solubility in non polar solvents

A

not soluble

54
Q

how would you describe ionic substances texture

A

brittle

hard and liable to breaking

55
Q

what bonds are present in covalent substances

A

covalent bond

56
Q

what is the bonding like in 2d networks like graphite

A

C bonded to 3 other C and 1 e- is delocalised which holds sheets together via temporary dipole

57
Q

what is the bonding like in 3D networks like diamond

A

C bond to 4 other C

58
Q

for covalent substances

what is the melting and boiling point relatively speaking and why

A

high

strong covalent bond

59
Q

for covalent substances

what is the conductivity and why

A

dont conduct

no free moving charges except in graphite due to delocalised e-

60
Q

for covalent substances

what is the solubility in all solvents

A

insoluble in all solvents

61
Q

for 3d covalent substances

what is the texture/strength and why

A

very hard 3D networks like diamond

due to strong directional bond

62
Q

what bonds and arrangement are present in metallic substances

A

atoms held in lattice structure via metallic bonds

metal atoms valence e- held loosely attracted to neighboring atoms nuclei = non directional

63
Q

for metallic substances

what is the melting and boiling points relatively speaking

A

high

64
Q

for metallic substances

what is the conductivity and why

A

conductors

moving valence e- form non directional bonding

65
Q

for metallic substances

what is the solubility and why

A

insoluble in all solvents

66
Q

for metallic substances

what is the density and why

A

high density

close packing

67
Q

for metallic substances

what is the texture and why

A

malleable and ductile

due to non directional bonding

68
Q

for metallic substances

what is the heat conductivity and why

A

good

atom vibrates and free e- transfer energy

69
Q

what are the 3 intermolecular forces

A

temporary dipoles

permanent dipoles

Hydrogen bonds

70
Q

what does a + enthalpy mean

A

energy is abosorbed

71
Q

what does a - enthalpy mean

A

energy is released

72
Q

what is the change in rH for exothermic reactions

A

negative

73
Q

what is the change in rH for endothermic reactions and what does this relate to bonds

A

positive

bonds broken

74
Q

what is the change in rH equation

A

change in rH = products - reactants

75
Q

what is the change in rH for endothermic reactions and how does this relate to bonds

A

positive

bonds formed

76
Q

what does a natural system tend towards for entropy

A

tends towards disorder

77
Q

is increased disorder or entropy + or -

A

+S

78
Q

what does a natural system tend towards for enthaply

A

tends towards decreased enthalpy (exothermic)

79
Q

what is the equation for double bond equivalents

A

DBE = 1/2 (2nC + nN - NH + 2)

where:
nC = number of carbons
nN = number of nitrogens
nH = number of hydrogens

80
Q

what are DBEs

A

number of rings or pi bonds present

81
Q

what are the 3 types of conformational isomers

A

sawhorse projections

newman projections

cyclohexane conformers (chair and boat)

82
Q

what are conformational isomers

what is the same and what is different

can it interconvert

A

same molecular formula and bonding sequence

different spatial arrangement

interconverts via rotation about single bond

83
Q

what are the 2 types of sawhorse projections and how are they related

A

staggered and eclipsed

related by one 60* rotation

84
Q

what is the most stable sawhorse projection

A

staggered = most stable

eclipsed = least stable

85
Q

what are the newmans projections viewed along carbon wise

A

viewed along C2-3

86
Q

how many newman projections are possible

A

4

87
Q

what are the 2 types of staggered and eclipsed newmans projections possible

A

staggered - anti
eclipse
staggered - gauche
eclipse - syn

88
Q

of the 4 newmans projections which are most and least stable

why is this

A

staggered - anti = most stable
eclipse
staggered - gauche
eclipse - syn = least stable

anti has largest groups greatest distance apart while syn has largest groups eclipsed

89
Q

which of the two is always more stable

A

staggered is always more stable than eclipsed

90
Q

what is the lowest energy conformation of a cyclohexane conformer

why

A

chair as its staggered

91
Q

how are the Hs designated on chair and boat conformers

A

chair = axial (up and down) and equatorial (sideways)

boat = no axial or equatorial as both ends are pulled up

92
Q

what is the highest energy conformation of a cyclohexane conformer

why

A

boat

as its eclipsing

93
Q

when you do a ring flip for a chair conformer what happens to the axial and equatorial H

what doesnt change about the H

A

axial becomes equatorial and vice versa

up and down dont change

94
Q

what do substituted cyclohexanes favor in terms of chair and boat conformers

A

favor conformation of chair that has largest atom in equatorial position

95
Q

what are configurational isomers

what is the same and what is different

can it interconvert

A

same formula and bonding sequence

spatial arrangement differ

convert via break/reformation of covalent bond

96
Q

what are the 2 types of configurational isomers

A

diastereomers

enantiomers

97
Q

what are the 2 types of diastereomers

A

cis/trans

E/Z

98
Q

what are E/Z used for

A

alkenes

99
Q

what is the Cahn ingold rules of priority

A

H < C < N < O < F < Cl < Br < I

100
Q

what are enantiomers

A

sp3 C with 4 different groups attached

chiral molecule

101
Q

what is R and S for enantiomers

A

Clockwise decrease = R

anticlockwise decrease = S

102
Q

what are meso compounds

A

mirror images but superimposable

103
Q

what happens in chromatography

A

mixture is adsorbed on polar stationary phase and polar mobile phase passed over it

104
Q

what does the polar solute do in chromatography in terms of what it is attracted to and its speed of movement

A

more attracted to polar stationary phase so moves more slowly

105
Q

what does the non polar solute do in chromatography in terms of what it is attracted to and its speed of movement

A

less attracted to polar stationary phase so moves rapidly

106
Q

what is homolytic cleavage

A

1 e- from bond ends up on each formerly bonded atom

107
Q

what bonds is homolytic cleavage seen in

A

non polar bonds

108
Q

what does homolytic cleavage produce

A

generates radicals

109
Q

what are radicals

A

neutral species with unpaired e-

110
Q

what is heterolytic cleavage

A

both e- of bond end up on one formerly bonded atom

e- always moves to electronegative atom

111
Q

what does heterolytic cleavage produce

A

produces + and -

112
Q

are carboanions or carbocations more common

A

carbocation

113
Q

order the following in order of most to least stable carbocations

methy, 2, 1, 3*

A

most stable = 3* > 2* > 1* > methyl = least stable

114
Q

what is the e- donor and acceptor in polar reactions

A

e- donor = nucleophile

e- acceptor = electrophile

115
Q

what are non polar reactions

A

reactions of free radicals

116
Q

what is Sn2 mechanism

A

bond break/make simultaneously in single step

117
Q

what is Sn1 mechanism

A

bond break the form in 2 steps

  1. heterolytic bond break forms reactive carbocation intermediate
  2. polar bond forms between nucleophile and electrophile
  3. heterolytic bond break forms neutral product