Atomic Orbitals & Molecular Orbitals Flashcards

1
Q

What is the hybridization of an atom that participates in resonance? What is the evidence?

A

One orbital lower (sp3 becomes sp2) & also the LP on the atom is in P
Evidence: atom has the ability to form a = bond w/ the other atom. So, we are using the LP e- to form a = bond & so cannot be in an sp2 or sp3 orbital

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2
Q

Why is tetrahedral N always achiral?

A

Bc its undergoes inversion so fast that its enantiomers form a racemic mixture

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3
Q

Can e- be present in antibonding orbitals?

A

Yes, but only 1. If there were 2 e- in antibonding orbitals, the compound would be unstable

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4
Q

Which is higher in energy, 2s or 2p? Wei shi ma? Porque?? Laai’sh?

A

2p is higher in E bc it has a node. Bc 2s doesn’t have a node, its e- can be closer to the nucleus in the 2s orbital

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5
Q

How does an electron behave?

A

Electron behaves as both a particle (e- orbits nucleus) and a wave (2 waves in ocean overlapping to create calm waters)

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6
Q

What did Schrodinger do?

A

Help us think of electrons as waves

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7
Q

What do we produce when we solve Schrodinger’s equation? What do these solutions describe?

A

Wave function (Y or psi) are the solutions, and wave functions describe orbitals

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8
Q

What do Schrodinger’s equations describe?

A

The location of a particular e-

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9
Q

Probability Density

A

How likely it is to find an e- in that volume
Probability density = psi^2 = orbital

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10
Q

What chance do you have of finding a 1s e- in its 1s orbital?

A

95%

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11
Q

Where is the s-block?

A

first 2 columns, including He

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12
Q

p-block location?

A

right side of periodic table

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13
Q

What do the + and - of orbitals mean?

A

it deals with the + and - sides of the wave function and nothing with the charge

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14
Q

What has lower energy 1s or 2s?

A

1s because e- closer to nucleus

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15
Q

Aufbau Principle

A

Orbitals fill in order of increasing energy (e- nearest to nucleus are more stable)

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16
Q

Pauli Exclusion Principle

A

Only 2 e- can occupy same orbital and their spins must be paired (draw 1 arrow up & another down)

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17
Q

Hund’s Rule

A

Fill orbitals of = E (degenerate) w/ 1 e- first and then double-fill when all full

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18
Q

Which atomic orbital lobe of p orbtial do e- go in?

A

Any (can put e- in same lobe or 1 in each lobe); but spin of e- is up

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19
Q

How should you write the e- configuration for p orbitals?

A

Separate them!
Ex:
1s2 2s2 2px1 2py1 2pz0
- fill x then y then z & then doublely fill

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20
Q

Hybridized Atomic Orbitals

A

Mixing of orbitals

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21
Q

Why do atomic orbitals hybridize?

A

To increase overlap when forming a bond and thus make the bond stronger and more stable
- more detail: when you hybridize, you bring in s-character to something that would otherwise have only had p-character & by bringing in this s-character, you bring the e- closer to the nucleus, which makes them more stable

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22
Q

How do you know the energy level of an orbital?

A

Look at the highest shell the element is in

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23
Q

How many hybrid orbitals do 4 AO’s make?

A

4

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24
Q

When will the s character in a hybridized orbital be bigger?

A

When the orbitals are in-phase

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25
Q

What are sp3 orbitals made from? How many of them are there?

A

2s, spx, 2py, 2pz. Makes 4 lobes on each side (8 total)

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26
Q

How many e- domain groups are in an sp3 hybridized C?

A

4

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27
Q

Angle of sp3 hybdrizied C?

A

109.5 degrees

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28
Q

sp3 shape?

A

tetrahedral

29
Q

What % of sp3 is s and what % is p?

A

s-character: 25%
p-chracter: 75%

30
Q

e- are more stable in which orbital, one with more s or p character? Why?

A

s-character bc closer to nucleus and thus can form bonds that are stronger (and shorter)

31
Q

How many e- domains in sp2?

A

3

32
Q

Angle of sp2 hybridized C?

A

120 degrees

33
Q

sp2 shape?

A

trigonal planar

34
Q

What % of sp2 is s and what % is p?

A

s-character: 33%
p-character: 67%

35
Q

What % of sp2 is s and what % is p?

A

s-character: 33%
p-character: 67%

36
Q

What are sp2 orbitals made from? How many of them are there?

A

2s, 2px, 2py, 2pz except one of the 2p orbitals is not hybridized

37
Q

How do you draw sp2 orbitals?

A

3 big lobes of sp2 (along w their smaller lobes) & 2 big lobes of p on either side

38
Q

Where do you put the e- in an sp2 hybridized C?

A

C has 4 e-, 1 will be in each lobe, (3 sp2 & 1 p) and there will be 1 empty p

39
Q

Where do you put the e- in an sp2 hybridized N?

A

N has 5 e-: 1 will be in each lobe, (3 sp2 & 1 p), and there will be two e- in 1 sp2 and 1 empty p

40
Q

How do you draw sp3 orbitals?

A

4 big lobes of sp3 (along w their smaller lobes)

41
Q

How do you show overlap in a drawing of orbitals?

A

Dashed line

42
Q

What orbitals overlap between 2 sp2 hybridized C?

A

the Ps in each C

43
Q

How many nodes in 3s?

A

2

44
Q

How many nodes in 3p? 2p?

A

3p: 2 (1 radial & 1 angular)
2p: 1

45
Q

Node (in MO context)

A

area with no e- density

46
Q

Angle in sp hybridized?

A

180 degrees

47
Q

What are sp2 orbitals made from? How many of them are there?

A

2s, 2px, 2py, 2pz except 2 of the 2p orbitals is not hybridized

48
Q

Amide

A

acyl (Carbonyl w/ R or H) bonded to N

49
Q

How many s3p2 hybridized orbitals can an atom make?

A

s: 3/5 = 60%
p: 2/5 = 40%
Can use up to s (100%) & p (300%)
- Can’t make 2 s bc will go beyond 100% (60%+60% = 120)

50
Q

How well can AO’s overlap?

A

Not completely bc then the nucleus would get too close & the nuclei would repel–called nuclear (+) repulsion

51
Q

How can we find an AO’s optimal overlap distance?

A

Lowest dip in an PE graph

52
Q

What type of interference do atomic orbitals depict when they hybridize to form MO’s?

A

Both constructive and destructive

53
Q

What is a bond in a bonding MO in terms of interference and probability?

A

An area of constructive interference (in-phase) & high e- probability when we look at psi^2 (wavefunction^2)

54
Q

What is a node in an antibonding MO in terms of interference and proability?

A

An area of destructive interference (out-of-phase) low e- probability when we look at psi^2 (wavefunction^2)

55
Q

Where is the e- density in a sigma bond? Pi?

A

Sigma: along axis
Pi: not along axis

56
Q

Bond order

A

(bondinge- minus antibondinge-)/2

57
Q

What BO can’t exist?

A

BO = 0 or less than 0 (neg) bc can’t have a bond if have = numbers of bonding and antibonding or if have more antibonding

58
Q

What is lower in energy? AO with s character or p?

A

more s = lower in energy (& more stable) bc closer to nucleus

59
Q

Why would O’s sp2 orbital be lower than C’s sp2 orbital?

A

Bc O is more EN & so can accommodate more e- & so more stable

60
Q

What is higher in energy, a pi made from p or a sigma made from sp2?

A

sigma made from sp2 is lower in energy bc sp2 is lower in E than p because it has s-character, which is closer to the nucleus & thus stabilizing

61
Q

When is the change in energy greater?

A

When the gap between HOMO-LUMO is smaller

62
Q

What happens if there is no energy match between HOMO & LUMO?

A

HOMO is lower than the LUMO

63
Q

If a molecule is higher in EN, will it be lower or higher than the orbital of the other molecule?

A

Higher in EN means lower in E

64
Q

How do you know how many nodes are in a Wavefunction graph for s orbitals

A

of times x = 0

or
energy level - 1

65
Q

How many radial nodes in 2p & 3p?

A

2p: 0
3p: 1

66
Q

Amine

A

Sp3, and all sigma/LP bonded to N

67
Q

How can u tell a nuclear node is present?

A

P orbital overlapping

68
Q

How to determine LUMO?

A

Draw orbital diagram & if it’s filled LP, can’t be that, so look for bonds bc they have antibonding too