Unit 2 (ch 12,18,14) Flashcards
1
Q
mixture of solid metals
A
alloys
2
Q
Use alloys to…
A
alter and improve properties of individual metals
3
Q
Metallic bonds consist of (blank)
A
shared electron pools
4
Q
Describe metallic bond
Are electrons easy or hard to pull away?
A
valence orbitals overlap with neighbors to give delocalized electron pool
-easy
5
Q
What happens when more metal ions bind together?
A
End up with a band of valence and/or conduction energy levels (valence and conduction bands)
6
Q
Semiconductors principle/explanation
A
valence and conduction bands are separated by a band gap, which varies in energy depending on compounds
7
Q
larger band gaps =
A
higher energy between the two bands, harder for electrons to move between them
8
Q
structures of metals
A
different, highly ordered ways that atoms can arrange to give a layer organization of metals
9
Q
What are unit cells?
A
smallest repeating units, stack together to form crystalline structure
10
Q
Dimensions of the unit cells are determined by
A
packing of atoms
11
Q
length of cubic
A
2r
12
Q
BCC radius
A
0.4330 times length
13
Q
FCC radius
A
0.3536 times length
14
Q
Alloys
A
different atoms either substitute or fit between the originals
15
Q
interstitial alloys
A
new atoms fit between the regular ones
16
Q
What type of hole has the most space?
A
cubic
17
Q
What is the ratio equation for the holes?
A
r guest/ r host
18
Q
What is the cubic holes ratio?
A
0.73-1.00
19
Q
NaCl is a compound where (blank) holes are filled by
A
octahedral, Na+ ions
20
Q
1st law of thermodynamics
A
energy not created nor destroyed, just transferred
21
Q
to determine the spontaneity of a process, we look at
A
entropy of system, surroundings, and universe
22
Q
2nd law of thermodynamics
A
energy wants to spread out
23
Q
Spontaneous means
A
no input is needed for the process to occur- doesn’t always happen fast
24
Q
microstates represent
A
unique arrangements of different options/states
25
by moving to areas of greater heat/energy or larger volumes, what happens?
more microstates are accessible and entropy increases
26
molecules have three types of motion/freedom- they are?
vibrational, translational, rotational
27
at lower temperatures, how does this affect microstates?
fewer accessible microstates, less energy to access more of them
28
colder things will spontaneously do what?
absorb energy from warmer ones- ice will melt, because liquid water has greater entropy
29
what processes are isothermal?
melting/freezing and boiling/condensation
30
define isothermal
energy goes to breaking molecules apart or bringing them together
31
What does it mean to be a state function? Example?
route from initial to final doesn't matter, only change and entropy
32
delta S system =
delta S final- delta S initial
33
delta S system =
qrev/T (K)
34
q=
heat that can leave or enter a system from the surroundings
35
what are forward and reverse processes?
melting and freezing are equal and opposite
36
for a process to be spontaneous, delta S univ must be
positive
37
delta S universe =
delta S system + delta S surroundings
38
Why does ice melt or water freeze spontaneously?
changes in temp give differences in the entropy for otherwise equal and opposite systems
39
dissolving a solid or diluting a solution is (blank)
- spontaneous
- solute molecules gain more freedom/disorder by entering system, even if some of the solvent molecules become slightly more ordered
40
interstitial
nonhost fills holes in host
41
substitutional
host replaced with non-host
42
types of substititutional
heterogeneous- clumps
| homogeneous- random, even distribution
43
solids are usually composed of
mix of elements
44
alloy
mixture of metals with the goal of improving the properties of metals (stronger, corrosion resistant, conductive)
45
what are a few examples of common alloys?
```
Brass (cu and zn)
Stainless steel (Fe and Cr)
```
46
metallic bond
shared pool of electrons where atoms are densely packed and valence orbitals overlap
47
band theory explains what?
sea of electrons
48
molecular orbits form
valence band
49
Are metals good conductors?
yes
50
semiconductors
- electronics
- valence and conduction bands separated by gap
- less energy by shifting atoms
51
doping semiconductors changes (blank)
band gap
52
if an element gives extra electrons it (blank)
raises valence bond
53
if an element gives holes- missing electrons it (blank)
lowers conduction band
54
if the element gives extra electrons it is known as the
n type (extra negative)
55
if the element gives holes, it is known as the
p type (extra positive)
56
no current means there is
no electron flow and electrons stuck in valence bond
57
current means there is
electron flow and electrons move from valence to conduction band
58
structures of metals
metal atoms can solidify in highly ordered "crystalline lattice"
59
hexagonal close packed (HCP) has what type of layering?
ababab
60
cubic close packed (CCP) has what type of layering?
abcabcabc and each atom touches 12 atoms
61
what type of cells have the densest packing?
HCP and CCP 74%
62
packing efficiency
volume of atoms/volume of cell x 100
63
Cubic
layers just stack on top of each other (52%)
64
What type of layer does cubic have?
aaaaaa
65
What type of layering does body centered cubic have?
ababab- 68%
66
unit cell dimensions are determined by what?
packing of atoms
67
simple cubic unit cell
length- 2r
one atom per unit cell
1 corner atom per unit cell
68
body centered cubic unit cell
length- r= 0.4330l
two atoms per unit cell
1 full in middle, 1 corner
69
face centered cubic
length- r= 0.2526l
4 atoms per unit cell
3 face, 1 corner
70
alloys
mixture of different metals
71
subsitutional alloy
-new metal atoms take place of original
72
3 types of subsitutional alloys
homogeneous
heterogeneous
intermetallic
73
homogeneous
randomly but evenly distributed
74
heterogeneous
clumps or groups of replaced atoms
75
intermetallic
uniform composition and stoichiometry
76
alloys can make metals
harder (harder for atoms to slide past each other)
77
interstitial alloy
host stays in pattern and holes are filled with other atoms
78
types of holes
tetrahedral
octahedral
cubic
79
tetrahedral
smaller, 4 host atoms, FCC and HCC
80
octahedral
larger FCC and HCC
81
cubic
middle of simple cube and when filled looks like BCC
82
radius of host: other RATIO
r other/ r host
83
what is the ratio for tetrahedral?
0.2:0.4
84
what is the ratio for octahedral?
0.4:0.7
85
what is the ratio for cubic?
0.7:1.0
86
if there is little carbon, the substance is often
malleable
87
metals are described as
cations in sea of electrons
88
what are the types of nonmental cystals?
covalent network
molecular solids
ionic solids
89
covalent network
solids held together by covalent bonds (e- sharing)
90
what forms network covalent solids?
C bonds
91
C-C bonds form
allotropes
92
diamond formation
4 covalent bonds, carbon (STRONG)
93
graphite formation
3 covalent bonds-carbon held together with dispersion
94
fullerenes
soccer ball shaped carbon bonds
95
molecular solids
molecular held together with imf
| range from H bonds and DD (H2O/ice) to ID weak forces holding solid together (CO2, O2S8)
96
ionic solids
cation and anion, ion-ion force
- bigger ion is in crystal lattice and one in hole
- maintain strict stoichiometric ratio
- ordered structure
97
Why don't ionic solids have alloys?
strict pattern and structure
98
solid, inorganic compound which has been heated
ceramic
99
what are common ceramics?
Si and SiO2 (silica)
100
amorphous solid
obsidion, no crystal lattice or order
101
Superconductors
atoms vibrating resist flowage (super cold = vibrating stops)
102
characteristics of metallic solids
malleable and breakable
103
characteristics of ionic solids
hard and brittle
104
what two types of structures have close packing?
HCC and FCC
105
what two types of structures have square packing?
BCC and SC
106
HCC stacking pattern
abababab
107
FCC/cubic closest packed stacking pattern
abcabc
108
BCC stacking pattern
ababab
109
SC stacking pattern
aaa
110
malleable means
easily bent and damaged
111
metallic elements have (blank) electronegatives than nonmetals
lower- bonding e not tight
112
(blank) has more valence than host semimetal
dopant
113
p type semiconductor
dopant has fewer valance electrons than host
114
meissner effect
magnet floating above superconducting material
115
1st law of thermodynamics
energy not created or destroyed, just transferred
| energy allows work
116
spontaneous vs nonspontaneous
do or don't require intervention of some sort
117
2nd law of thermodynamics
entropy helps determine spontaneity
energy wants to spread out
universe tends to disorder
118
for a spontaneous process, the entropy of the universe (blank)
increases
119
Microstates
unique arrangement of things
-arrangement is energy level
deflating tire
120
three types of motion for gas molecules
translational, rotational, virbrational
121
Boltzmann distribution
- indiv. molecules might change energy but system stays same
| - shows all possible states a molecule can occupy
122
higher temp or greater volume gives (blank)
more potential microstates
123
more microstates means
increased entropy
124
colder things spontaneously (blank)
absorb energy from warmer things
125
melting and boiling processes are (blank)
isothermal
126
entropy is a (blank)
"state function"
127
what does it mean if something is a "state function"
only initial and final states matter
128
delta S system
S final - S initial
129
delta S system or entropy for isothermal process
q reversible/ T (k)
130
forward and reverse processes are
equal
131
S univ =
S sys + S surroundings
132
heat transfer to cooler system is
spontaneous
133
greater temperature difference =
greater entropy change for univ
134
entropy related to dissolving solutes in solvents
gain freedom of motion once dissolved
135
dilution process is
spontaneous- more disorder
136
3rd law of thermodynamics
at 0 K, entropy=0
137
Gibbs free energy
delta Hrxn - T(delta S)
138
If G < 0, S univ
>0 spontaneous
139
If G>0, S univ
<0 nonspontanous
140
If G = 0
no change in system
141
```
delta H (-) and delta S (+)
delta G =
spontaneous or nonspontaneous?
```
delta G <0
| spontaneous
142
```
delta H (-) and delta S (-)
delta G =
spontaneous or nonspontaneous?
```
delta G <0 at lower temp
| spontaneous at lower temp
143
```
delta H (+) and delta S (+)
delta G =
spontaneous or nonspontaneous?
```
delta G <0 at high temp
| spontaneous at high temp
144
```
delta H (+) and delta S (-)
delta G =
spontaneous or nonspontaneous?
```
delta G>0
| not spontaneous
145
What is the 3rd law of thermodynamics?
"perfect" crystalline material at 0 K, entropy = 0
146
What does Gibbs free energy relate?
delta S and H sys and the energy available to do work
147
If delta G = <0, delta S univ > 0, spontaneous or nonspontaneous?
spontaneous
148
If delta G > 0, delta S univ < 0, spontaneous or nonspontaneous?
nonspontanous
149
if delta H is - and delta S is + , delta G is? Spontaneous?
always < 0, always spontaneous
150
if delta H is - and delta S is - , delta G is? Spontaneous?
< 0 at lower temp, spontaneous at lower temp
151
if delta H is + and delta S is + , delta G is? Spontaneous?
< 0 at higher temp, spontaneous at higher temp
152
if delta H is + and delta S is - , delta G is? Spontaneous?
always > 0, never spontaneous
153
system becomes colder, q rev is (blank)
+ (gaining energy)
154
system becomes hotter, q rev is (blank)
- (losing energy)
155
What is an example of a coupled reaction?
delta G can power other reactions that are nonspontaneous- combustion of glucose drives ADP phosphorylation to form ATP
156
kinetics is the study of
rates of reactions
157
Describe catalytic converters in cars
remove NO
158
production rate is
+
159
consumption rate is
-
160
slope =
- rate
161
the overall reaction order is the
sum of the exponents
162
increased molecules and concentration (blank) rate
increases
163
if a line is linear, it is
first order
164
pseudo first order
one of reactants is way larger than the other so it becomes the only one that matters
165
step 1 is the (blank)
slowest
166
rate determining step
slowest step
167
if collisions are increased, (blank) increases
concentration
168
subscripts tell us what?
reaction order
169
overall rate depends on the (blank) in the rate determining step?
concentrations
170
1st order reaction in relation to graph
if ln(x) vs t is straight line
171
activation energy equation
ln (k2)- ln (k1) = Ea/R (1/T2-1/T2)
172
higher Ea =
slower reaction
173
if Ea is smaller, reaction is
faster
174
if Ea is larger, reaction is
slower
175
if the graph starts at higher energy then goes to lower, the reaction is going to be (blank) and delta H is going to be (blank)
exothermic, negative
176
if the graph starts at lower energy and goes to higher energy, the reaction is going to be (blank) and delta H is going to be (blank)
endothermic, positive
177
how to find slope
ln(k1)-ln(k2)/ (1/T1-1/T2)
178
Reaction mechanisms describe what
molecularity
179
unimolecular
one molecule in rate
180
bimolecular
two molecules
181
three molecules
ter
182
step 1 is the
rate determining step, slow
183
rate laws are determined by
the slowest step
