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Core Chemistry 1A - Paper 1 > Structure and Bonding > Flashcards

Structure and Bonding Flashcards

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1
Q

E =

A

n^2h^2 / 8(me)L^2

in 2D n^2 becomes n^2 + m^2

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2
Q

3 angular wave functions of p orbitals

A

px, (orbital horizontal, x horizontal axis, y vertical axis)
py, (orbotal vertical, x horizontal axis, y vertical axis)
pz, (orbital horizontal, z horizontal axis, x vertical axis)

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3
Q

Half equations: IO3 - goes to what in 4 - 9M HCl?

A

ICl2 -

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4
Q

Define quantize

A

To restrict a quantity to one of a fixed set of numbers

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5
Q

What is the experimental evidence for electrons behaving as both a particle and a wave

A

The photoelectric effect - many metals emit electrons when light shines on them. Increasing intensity of light increased number of electrons emitted, but not their kinetic energy - so electrons behave as particles

Davisson and Germer (1925) - Fired electrons at nickel. Electrons diffracted not just reflected - a property of waves

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6
Q

De Broglie relation

A

λ = h /mv

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7
Q

KE =

A

Curvature = 2nd derivative

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8
Q

Typical bond length in a molecule

A

100 pm

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9
Q

A very small wavelength means…

A

no diffraction

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10
Q

What is the potential energy of an electron confined to a 1D box?

A

0 inside the box, infinity at the walls

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11
Q

What is the wavefuntion, ψ?

A

Wave height at point x

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12
Q

When you put an electron in a box…

A

It behaves as a wave

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13
Q

ψn(x) =

A

Csin(nπx / L)

L = length of box
n = quantum number
C = normalisation constant, value needed to make integral of this 1
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14
Q

What is a node?

A

Locus where the wavefuntion is 0

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15
Q

What is ψ^2?

A

The probability of finding the electron at that point

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16
Q

ψ(n,m) (x,y)

A

2/L sin(nπx/L) sin(mπy/L)

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17
Q

Quantum number n =

A

Orbital size quantum number - principle quantum number

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18
Q

Quantum number l =

A

Orbital shape quantum number - orbital angular momentum quantum number

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19
Q

Quantum number ml =

A

Orbital orientation quantum number - magnetic quantum number

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20
Q

Orbital is another word for…

A

hydrogen wave function, ψ

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21
Q

What does it mean to say that the electron can behave as a wave as long as it’s a standing wave?

A

The wave must be continuous, and there must be an integer number of waves around the ring

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22
Q

2πr =

A

nλ

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23
Q

What is the radial wavefunction?

A

Depends on radius r, quantum number n = 1,2,3,4….

Uses symbol ψ(r)

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24
Q

What is the angular wavefunction?

A

Depends on θ, ϕ, quantum numbers l (0 , 1, …. , n-1) and ml (-l, …, +l)
Uses the symbol ψ(θ, ϕ)

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25
Q

What is needed to give a wavefunction in spherical polar coordinates?

A

Radius, r

Colatitude (angle down from z axis), θ

Azimth (angle east from x-z plane), ϕ

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26
Q

What quantum numbers give a 1s wavefunction?

A

n = 1
l = 0
ml = 0
(s means l = 0)

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27
Q

Radial distribution function =

A

4πr^2ψ^2

The probability of finding the electron in all directions at that radius

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28
Q

How many radial nodes does an ns wavefunction have?

A

n-1

np = n-2
nd = n-3
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29
Q

Total wavefunction =

A

ψ(r)ψ(θ,ϕ)

30
Q

Angular wave functions for all s wave functions are…

A

spherical

31
Q

What is the boundary surface?

A

A representation of the angular wavefunction that contains 90% of the electron density

32
Q

If 2 energy states are degenerate they…

A

have the same energy

33
Q

What is the Pauli Exclusion Principle?

A

No 2 electrons in an atom or ion can have all their quantum numbers the same

34
Q

What is Hand’s rule of maximum spin multiplicity?

A

Lowest energy = maximum number of parallel spins

35
Q

For hydrogen, orbital energy is proportional to…

A

-1/n^2

36
Q

For atoms other than hydrogen, orbital energy is proportional to…

A

-Zeff^2 / n^2

37
Q

Order of repulsion of electron pairs (strongest to weakest)

A

Lone pair - lone pair
lone pair - bonding pair
Bonding pair - bonding pair

38
Q

Shape and bond angle of molecule with 2 electron pairs

A

Linear

180

39
Q

Shape and bond angle of molecule with 3 electron pairs

A

Trigonal planar

120

40
Q

Shape and bond angle of molecule with 4 electron pairs

A

Tetrahedral

109.5

41
Q

Shape and bond angle of molecule with 5 electron pairs

A

Trigonal bipyramid
90 and 120
Equatorial larger site

42
Q

Shape and bond angle of molecule with 6 electron pairs

A

Octahedral

90

43
Q

Shape and bond angle of molecule with 7 electron pairs

A

Pentagonal bipyramid
90 and 72
Axial larger site

44
Q

What is Bent’s rule? (VSEPR)

A

The smaller atom goes to the smaller site

45
Q

Why do we need to create orbital hybrids?

A

Because for overlap we need singly occupied orbitals

46
Q

What hybridisation does forming a linear molecule require?

A

sp

47
Q

What hybridisation does forming a trigonal planar molecule require?

A

sp2

Taking s, px, py and 3 hybrids at 120degrees in the xy plane

48
Q

What hybridisation does forming a tetrahedral molecule require?

A

sp3

Taking s, px, py and 4 hybrids directed at the vertices of the tetrahedron

49
Q

The anti bonding orbital is denoted by…

A

σu* or πg*

50
Q

The bonding orbital is denoted by…

A

σg or πu

51
Q

Bond order =

A

(no of bonding electrons - no of anti bonding electrons) / 2

52
Q

What does paramagnetic mean?

A

A material is paramagnetic if it is attracted to a magnet because of unpaired electrons

53
Q

What does diamagnetic mean?

A

A material is diamagnetic if it is repelled by a magnet because of paired electrons

54
Q

Molecular orbitals are…

A

linear combinations of atomic orbitals

55
Q

Magnetic moment, X =

A

diamagnetic - paramagnetic

56
Q

For diatomic molecules with p orbitals, σu* =

A

1/√2 [pz(a) + pz(b)]

57
Q

For diatomic molecules with p orbitals, σg =

A

1/√2 [pz(a) - pz(b)]

58
Q

For diatomic molecules with p orbitals, πu =

A

1/√2 [px(a) + px(b)]

59
Q

For diatomic molecules with p orbitals, πg* =

A

1/√2 [px(a) - px(b)]

60
Q

Bond order will correlate with…

A

Bond length and bod strength

61
Q

J in SI base units

A

kg m^2 s^-2

62
Q

What is excitation energy?

A

The energy required to move and atom to its next energy level

63
Q

1 mile =

A

1609 m

64
Q

What is more penetrating, 2p or 2s?

A

2s

65
Q

If an orbital is more penetrating, it feels…

A

a higher Zeff

66
Q

What is penetration?

A

The attraction an orbital feels towards the nucleus

67
Q

How to show if an orbital has a higher Zeff than another

A

Sketch the radial distribution functions, whichever has a local maximum closest to the nucleus feels a higher Zeff

68
Q

State and explain for which elements sp switching occurs

A

B, C and N

2p orbitals are not involved with elements before B. After N, the energyy gap between 2s and 2p is too large

σg and πu switch

69
Q

Describe the 1s, 2s and 3s wavefunctions and radial wavefunctions

A

All start at not 0,
Have 0, 1 and 2 nodes respectively and tend towards x axis
Radial wavefunctions are bumps, starting at 0, going to 0 at nodes, tending towards x axis

70
Q

Describe the 2p and 3p wavefunctions and radial wavefunctions

A

Start at 0, go up first
Have 0 and 1 nodes respectively
Tend towards x axis
Radial wavefunctions are bumps, starting at 0 going to 0 at nodes, tending towards x axis

71
Q

Describe the 3d wavefunction and radial wavefunction

A

Starts at 0, goes up first, no nodes
Tends towards x axis
Radial wavefunction similar shape, goes up higher, more like a bell

Core Chemistry 1A - Paper 1 (2 decks)

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