Chem Quix #4 Flashcards

1
Q

Octet Rule Exceptions

A

1) Odd e- molecules
2) Hypovalent (e- deficient molecules)
3) Hypervalent molecules (valence shell expansion)

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2
Q

Odd e- molecules

A

Moleulce w/ odd e- can’t have octet for every atom
ex. NO w/ 11 valence e- or NO2 w/ 17 valence e-

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3
Q

Hypovalent Molecules

A

atoms w/ less then octet configuration
ex. BH3 & BF3

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4
Q

Hypervalent Molecules/Valence Expansion

A

molecules APPEAR to have atoms w/ more then octet of e- in valence shells but it’s maintained
ex. XeF2 (8e- + 2e- = 10e-) or PF5 (5+5=10e-) or SF6 (6+6=12)

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5
Q

Formal Charge

A

charge on atom in molecule if e- pair bonds are hypothetically broken (homolyticially)

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6
Q

Heterolytically

A

breaking covalent bond so e- pair is transferred to 1 of the partners (usually more electron(-)…resulting charges = oxidation states

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7
Q

2 extremes of formal assignment of bonding e- pairs

A

formal charge & oxidation states

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8
Q

Diff. between formal charge & oxidation #

A

FC = assuming equal sharing of e- VS Ox. # =assuming interaction is 100% ionic (transfer)

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9
Q

Neither FC or Ox # describe _____________ & actual charge is _____________

A

Neither FC or Ox # describe bonding in HETERNUCLEAR DIATOMIC MOLECULES & actual charge is INTERMEDIATE

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10
Q

Rules for Ox. #s

A

1) must add up to molecule charge
2) is always 0 in elemental form
3) nonmetals have (-) Ox. #s

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11
Q

Ox. # Rule Exceptions

A

1) Oxygen has Ox. # of -2 EXCEPT when combined w/ Flourine
2) Oxygen has Ox. # of -2 EXCEPT when combined w/ O-O bond
3) Ox. # of Hydrogen is +1 w/ nonmetals (EXCEPT B or Si)and -1 when bonded w/ metals

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12
Q

sum Ox. #s =

A

charge on molecule

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13
Q

VESPR

A

don’t account for lone pairs (repulsion between e- lone pairs is minimized)

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14
Q

In Ox. #s 1 valence e- pair =

A
  • 1 single bond
  • 1 double bond
  • 1 triple bond
  • 1 lone pair
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15
Q

Steric #

A

atoms bonded
(coordination # + lone pair #)

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16
Q

explain AXE notation

A

A: just is
X: coordination #
E: lone pair #

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17
Q

When is compound usually expressed w/ VESPR?

A

when X + E = steric #

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18
Q

Lone Pair Size & effects

A

larger than bond pair & thus repulsions are greater resulting in decreasing bond angle

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19
Q

Molecules w/ steric #5

A

Trigonal Bipyramidal (AX4E)

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20
Q

Trigonal Bipyramidal sites for lone pairs

A

axial & equatorial

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21
Q

Trigonal Bipyramidal isomers

A

has 2 depending on if lone pairs occupy axial or equatorial sites

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22
Q

Trigonal Bipyramidal preferred bonding site

A

equatorial (more spacious w/ 2 90 angles instead of 3 90 angles)

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23
Q

Octahedral preferred bonding site

A

sites separated by 180

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24
Q

Which is the most dominant & why?
lone pair-lone pair
lone pair-bond pair
bond pair-bond pair

A

lone pair-lone pair since they are closest to the central atom

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25
Q

Molecular Orbital Theory

A

account for lone pairs

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26
Q

e- moving in circular orbit will

A

lose its energy and spiral into the nucleus

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27
Q

What will an electric charge that undergoes acceleration (changes in velocity & direction) emit?

A

electromagnetic radiation & will lose energy w/ every turn

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28
Q

Synchrotron

A

beam of e- spinning & changes path to emit radiation

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29
Q

Quantization

A

examines radiation emitted from materials

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30
Q

Light

A

wave, particle, or energy

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31
Q

most electronic structure of atoms comes from analysis of

A

light emitted/absorbed by substances

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32
Q

Newton’s light discovery

A

light can be broken down into components w/ diff. color from red to violet w/ prism (ROYGBIV)

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33
Q

Wave lengths from longest to shortest (lowest frequency to highest)(lowest energy to highest)

A

Radio Waves
Microwaves
Infrared Radiation
(ROY G BIV)
Ultraviolet
Gamma Rays
Cosmic Radiation

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34
Q

3 Features of a Wave

A

1) Amplitude
2) Wavelength
3) Frequency

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35
Q

Wave Amplitude

A

max displacement (height above midline)

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36
Q

Wave Intensity

A

determines radiation levels (amplitude^2)

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37
Q

Wave Wavelength

A

peak-peak distance

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38
Q

Wave Frequency

A

wavelengths that pass through a given point in 1 second

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39
Q

1/s =

A

Hz

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40
Q

Speed eq.

A

distance frequency x wavelength
————- = ————————————
time 1

41
Q

Distance eq.

A

frequency x wavelength

42
Q

Sqeed eq. expanded

A
43
Q

C in relation to frequency & wavelength

A

C = wavelength x frequency

44
Q

Speed of Light in a vacuum (c)

A

3x10^8
- will have diff. speeds in diff. medians but never faster

45
Q

Frequency in relation to C & wavelength

A

Frequency = c/wavelength

46
Q

High Frequency has ____________ wavelength & ___________ energy?

A

Short wavelength
High Energy
ex. red light

47
Q

Low frequency has ____________ wavelength & ___________ energy?

A

Long wavelength
Low Energy
ex. violet light

48
Q

Node

A

where magnetic field & electric filed intersect at 0

49
Q

light electromagnetic radiation

A

oscillating electric & magnetic field perpendicular to direction in which the light is propagating

50
Q

Electric fields exert an influence on

A

particle changes

51
Q

Magnetic fields exert an influence on

A

moving charged particles

52
Q

Electromagnetic

A

has large range of wavelength & frequencies w/ no limit

53
Q

Red light

A

Low frequency
Long wavelength

54
Q

Ultraviolet light

A

High frequency
Short wavelength

55
Q

Infrared light

A

corresponds to the heat we feel from a hot object

56
Q

What did black body radiation, photoelectric effect, & atomic spectra prove?

A

Objects can’t lose or gain energy in arbitrary or continuous amounts

57
Q

Explain Black Body Radiation Experiment

A

put _______ into black body and w/ it bouncing off…examined color shift of BBR & demonstrated that the wavelength corresponds to the mas is INVERSELY proportional to the temp.

58
Q

ex. of red hot and white hot heat

A

red hot = stove top burning
white hot = incandescent bulb

59
Q

Black body radiation is a function of

A

temp. & total intensity over all wavelengths is proportional to the power of temp.

60
Q

max @ 1000K is shorter then that for

A

800K

61
Q

Photons in a black box as an analogy for Oscillators

A
62
Q

Black box

A

box that absorbs all photons incident upon it & re-radiates the photons till they reach thermal equilibrium

63
Q

Ultraviolet Catastrophe

A

Any object @ non-zero temp. would emit intense ultraviolet radiation (even X-Rays) & would devastate the countryside
- Breaks law of conservation of energy

64
Q

Rayliegh’s results

A

black body should emit an infinite amount of energy (breaks law of conservation of energy)

65
Q

moles per unit frequency per unity volume eq.

A

8piv^2/c^3

66
Q

increased frequencies you can fit _________ modes into the cavity

A

more because shorter wave lengths (2x frequency = 4x modes)

67
Q

Basis for Classical Calculations

A

radiated photons (electromagnetic waves) can be considered to be produced by standing waves (resonant modes) in the cavity which is radiating

68
Q

Standing waves

A

resonant modes

69
Q

radiated photons

A

electromagnetic waves

70
Q

BBR Classical Theory

A

intensity INCREASES as frequency INCREASES
- that matter can absorb/emit any energy quantity
- didn’t predict region

71
Q

BBR Experimental Results

A

max value of inensity exists as a function of wavelength

72
Q

What would happen to humans in ultraviolet catastrophe?

A

Our bodies would glow in the dark but there wouldn’t be any darkness to glow in

73
Q

How must an oscillator gain & lose energy?

A

In quanta of magnitude h x frequency where H is plank’s constant

74
Q

Plank’s Constant

A

6.63x10^-34 J s

75
Q

Classical Oscillator

A

has CONTINUOUS values of energy and can gain or lose energy in arbitrary amounts (ramp)

76
Q

Quantum Oscillator

A

has DISCRETE energy levels & can only gain & lose energy in discrete amounts (steps that can’t be climbed if not enough energy to reach next level)

77
Q

Low frequency oscillators have (occupied or unoccupied) levels?

A

Occupied energy levels

78
Q

High frequency oscillators have (occupied or unoccupied) levels?

A

Unoccupied energy levels

79
Q

What eq. shows radiation of frequency from oscillating atom releasing energy into its surroundings?

A

Frequency = energy / h

80
Q

What is intensity of radiation?

A

energy packets generated by ind______
- measured in energy

81
Q

Planks Hypothesis

A

radiation of frequency can only be generated if enough energy is available since atoms of a cool body don’t have enough energy to generate a high frequency UV radiation (ultraV. cat. is avoided)

82
Q

Planks Law
deltaE:
n:
h:
v:
hv:

A

deltaE = nhv
n: integer #
h: 6.63x10^-34
v: radiation frequency
hv: energy quanta

83
Q

Photoelectric Cell (photocell) experiments by H. Hertz

A

ultraviolet radiation strikes a metal surface in vacuum & the ejected e- are attracted to (+) charged collector & a current flows

84
Q

Photoelectric Effect Observations

A

1) max kinetic energy of e_ doesn’t increase as intensity of light increases (more e- emitted)
2) no e- emitted unless radiation has frequency above threshold value characteristic of that meta
3) e- ejected immediately regardless of how low intensity of radiation
4) kinetic energy of ejected e- increase linearly w/ frequency of incident radiation

85
Q

Red light shown onto metal:
Low intensity purple light on metal:
High intensity purple light on metal:

A

Red: frequency too low, no e- ejected from metal & no electric current flows
Low purple: above threshold frequency so SOME e- ejected from metal; small current
High purple: above threshold frequency so MANY e- ejected from metal; high current

86
Q

Einstein said electromagnetic radiation consists of ___________?

A

Particles (photons)
E=h x frequency

87
Q

Photon

A

packets of energy related to frequency

88
Q

Do photons of blue light or red light have higher energy?

A

Blue light photons

89
Q

When energy of photon less the threshold, how does intensity effect e- ejection?

A

It doesn’t…almost or far away are both not THERE

90
Q

When energy of photons is more than threshold, what is excess energy and how does it effect ejected e-?

A

appears as Kinetic energy of the ejected e-

91
Q

How does light eject e- from metal?

A

When light (photon particles) strikes metal, the energy is transferred to e-. If energy to e- is sufficient, it’ll overcome the attractive forces & e- will be ejected.

92
Q

How does light frequency effect photoelectron kinetic energy?

A

Linearly after threshold

93
Q

How does light intensity effect photoelectron kinetic energy?

A

It’s a constant

94
Q

Work Function

A

barrier that e- must overcome to escape from surface (initial hv)

95
Q

Kinetic Energy eq.

A

KE = hv - work function (initial hv)
- intercept (work function) depends on metal but slope (h) is constant

96
Q

hv in terms of KE & work function

A

hv = KE + work function

97
Q

Kinetic energy of e-

A

.5m(sub e) v^2 + (initial hv)

98
Q

E in terms of h and frequency

A

E = h/frequency

99
Q
A