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CHEM 231 > Quiz 1 - Solids > Flashcards

Quiz 1 - Solids Flashcards

1
Q

Define crystal structure

A

3D arrangement of atoms

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2
Q

Solids can be one of two types

A

crystalline or amorphous

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3
Q

Define crystal lattice

A

pattern formed by repeating structural elements

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4
Q

Define unit cell

A

smallest repeat unit of a crystal structure that reproduces the crystal in 3D

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5
Q

List the 7 crystal systems

A

Cubic, tetragonal, orthorhombic, monoclinic, triclinic, trigonal, hexagonal

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6
Q

What is the relationship between lattice parameters for orthorhombic?

A

a does not equal b does not equal c, A=B=Y=90

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7
Q

What is the relationship between lattice parameters for rhombohedral (trigonal)

A

a=b=c, A=B=Ydoesnt= 90

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8
Q

What is the relationship between lattice parameters for tetragonal?

A

a=bdoesnt=c, A=B=Y=90

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9
Q

What is the relationship between lattice parameters for hexagonal?

A

a=bdoesnt=c, A=B=90, Y=120

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10
Q

What is the relationship between lattice parameters for cubic?

A

a=b=c, A=B=Y=90

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11
Q

ABA = what? ABC = what?

A

ABA = hexagonal close packed, ABC = cubic close packed

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12
Q

CCP and HCP have the same ___

A

packing density (74%) and Cn = 12

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13
Q

How many holes in CCP and HCP? How big are they?

A

N octahedral holes, 2N tetrahedral holes
Octahedral hole is 0.41r, tetrahedral is 0.23r

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14
Q

What is an example of non close packing?

A

BCC body centered cubic

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15
Q

What is the packing density of BCC?

A

68%

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16
Q

Are ionic structures truly close packed CCP or HCP?

A

no, eutectic, anions dont actually touch due to electrostatic replusion

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17
Q

The radius of the cation must be ____ than the hole it sits in?

A

greater

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18
Q

What do the different CNs mean in a unit cell?

A

structure but not shape of cell
CN = 8 = cubic
CN = 6 = octahedral
CN = 4 = tetrahedral
CN = 3 = trigonal planar
CN = 2 = linear

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19
Q

Give an example of an AB structure with CN = 8 (cubic)

A

CsCl - cubic

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20
Q

Give an (2) example of an AB structure with CN = 6 (octahedral)

A

NaCl - cubic
NiAs - hexagonal

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21
Q

Give an (2) example of an AB structure with CN = 4 (tetrahedral)

A

ZnS (zinc blende) - cubic
ZnS (Wurtzite) - hexagonal

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22
Q

Give an example of an AB2 structure with CN = 8-4, 6-3, 4-2,

A

CaF2 (fluorite) - cubic
TiO2 (Rutile) - tetragonal
SiO2 (Cristabolite) cubic

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23
Q

Give an example of an A2B structure

A

Anti fluorite K2O

24
Q

If the radius ratio is 0.225-0.414 then…

A

AB - ZnS (ccp and hcp)

25
Q

If the radius ratio is 0.414-0.732 then….

A

AB - NaCl (ccp), NiAs (hcp)
AB2 - TiO2

26
Q

If the radius ratio is 0.732-1 then…

A

AB - CsCl
AB2 - CaF2

27
Q

What is the shottky defect?

A

missing atoms, charge has to be neutral

28
Q

What is the Frenkel defect?

A

Displacement into interstitial sites

29
Q

What is anti site disorder?

A

+/- atoms are swapped in one spot

30
Q

What is an extrinsic defect?

A

If an atom of less or more charge is inserted into a structure, defects in sites having opposite charges will occur to balance

31
Q

How do you determine the set of quantum numbers for a given element?

A

n= energy (shell) 1,2,3,4
l = s,p,f,d 0,1,2,3 (n-1)
ml = l to -l

32
Q

What is a node?

A

part in the function where the probability of finding an electron drops to 0

33
Q

What are the exceptions for electron configurations?

A

Cr = [Ar] 4s1 3d5
Cu = [Ar] 4s1 3d10

(Same for 4d analogues - Mo and Ag)

34
Q

How do you calculate effective nuclear charge in this course?

A

Zeff = #protons - #core electrons (not valence)

35
Q

VESPER - 2 things

A

EPG = Linear
- 0 LEP = Linear

36
Q

VESPER - 3 things

A

EPG = Trigonal Planar
- 0 LEP = Trigonal Planar
- 1 LEP = Bent

37
Q

VESPER 4 things

A

EPG = Tetrahedral
- 0 LEP = Tetrahedral
- 1 LEP = Trigonal Pyramidal
- 2 LEP = Bent

38
Q

VESPER 5 things

A

EPG = Trigonal Bipyramidal
- 0 LEP = Trigonal Bipyramidal
- 1 LEP = See Saw
- 2 LEP = T shaped
- 3 LEP = Linear

39
Q

VESPER 6 things

A

EPG = Octahedral
- 0 LEP = Octahedral
- 1 LEP = Square pyramidal
- 2 LEP = Square planar

40
Q

Define the Pauli Exclusion principle

A

No two electrons in the same atom can have the same 4 QNs

41
Q

Define Hunds rule

A

Degenerate orbitals are occupied separately by electrons with parallel spins

42
Q

Ionization energy __ left to right and __ down

A

increases, decreases

43
Q

Electronegativity ___ left to right

A

increases

44
Q

Define constructive and destructive interference

A

Constructive - amplitude increases - more likely to find an electron here - bonding orbitals

45
Q

Paramagnetic vs Dimagnetic?

A

Para = spins parallel (unpaired) - attracted to mag field
Dia = spins paired - repelled from mag field

46
Q

E neg differences?

A

0 - covalent
0.1-0.4 - NP covalent
0.5-1.7 - P covalent
Greater than 1.7 = Ionic

47
Q

The more e neg atom contributes more to the ___ orbital

A

bonding (opposite applies)

48
Q

greater bond order = ___ bond strength = ___ bond length

A

greater, shorter (cuz pulling closer)

49
Q

What is the difference between the MO energy diagrams between the diagram for Li - N and O - F?

A

Li - N is (bottom up) sigma sigma pi sigma pi sigma
O - F is sigma sigma sigma pi pi sigma

2P is 2 down from top
- 2S goes to 1,2,4 - 2P goes to 2,3,4,5,6 (Li - N)
- 2S goes to 1,2 - 2P goes to 3,4,5,6 (O - F)

50
Q

rule for transition metal ionizations with electron configurations?

A

if its a plus charge - remove from the 4s before the 3d

51
Q

why are lewis diagrams bad?

A

no prediction of 3D structure or contributuion of resonance

52
Q

Why is VSEPR bad?

A

works bad with heavy elements
- must hybridize

53
Q

Why is VB bad?

A

need lewis structure first
- describes bonding but not energies

54
Q

When is MO theory bad?

A

great predictor of energies but not good for determining structure

55
Q

for heteronuclear diatomics we do not use?

A

EX) IBr
- we do not use g and u

CHEM 231 (3 decks)

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