final exam review Flashcards
(211 cards)
1
Q
what are sp hybrid orbitals
A
orbitals formed by mixing one s and one p orbital of a central atom
2
Q
what is hybridization
A
a theoretical process of orbital mixing to form hybrid orbitals
3
Q
what does the formation of bond orbitals mean
A
the wave functions of the electrons are in phase
4
Q
what is the basic principle of valence bond theory
A
a covalent bond forms when orbitals of two atoms overlap and a pair of electrons occupy the overlap region
5
Q
what does greater electronegativity difference result in
A
larger partial charges and higher partial ionic character
6
Q
what is ON equal to
A
the number of valence electrons minus the number of shared electrons plus the number of unshared electrons
7
Q
what is an oxidation number
A
the charge that an atom would have if all of the atoms attached to it were removed along with the electron pairs it is sharing with other atoms
8
Q
electronegativity is ________ related to atomic size. why?
A
inversely related. the nucleus of a smaller atoms is closer to the shared pair than the nucleus of a larger atom
9
Q
in substances what are most atoms joined by
A
polar covalent bonds, partly ionic and partly covalent
10
Q
what makes a good fuel
A
covalent compounds with weak bonds and relatively less O
11
Q
what is a fuel
A
a material that reacts with atmospheric oxygen to release energy
12
Q
what is delta H r related to
A
sigma delta H reactant bonds broken + sigma delta H product bonds formed or sigma BE reactant bonds broken minus sigma BE product bonds formed *these are only for gas phase reactions
13
Q
are covalent substances generally good conductors
A
no, electrons are localized and no ions are present
14
Q
do molecular covalent substances have high melting and boiling points
A
no they have low mp and no because they have strong bonding forces between atoms within the molecule and weak intermolecular forces between separate molecules
15
Q
do network covalent solids have a high melting and boiling points? why?
A
yes due to the large amount of energy required to rearrange covalent bonds
16
Q
the trend in bond lengths is __________ to the trend in bond energy
A
opposite
17
Q
as we go left across a group what does bond length do
A
increases
18
Q
what does a higher bond order result in
A
a shorter bond length and higher bond energy
19
Q
strong bonds are ______ in energy while weaker bonds are __________ in energy
A
lower, higher
20
Q
why is bond energy always positive
A
bond breakage is an endothermic process
21
Q
what is electron affinity
A
the energy change accompanying the addition of 1 mol of electrons to 1 mol of gaseous atoms of ions
22
Q
what does the magnetic quantum number prescribe
A
the 3-d orientation of the orbital in the space around the nucleus
23
Q
what are orbitals
A
mathematical solutions to the schrödinger wave equation
24
Q
what are orbitals
A
mathematical solutions to the schrödinger wave equation
25
what does a higher nuclear charge do
it increases nucleus-electron attractions, lowering sub shell energy and stabilizing the atom
26
what is special about hydrogen and it’s energy state
it’s the only atom whose energy state depends completely on the principal quantum number
27
what does the principal quantum number specify
the energy level (shell) of the H atom, the higher the n value the higher the energy level
28
what is the principal quantum number
a positive integer that indicates the relative size of the orbital and therefore the relative distance from the nucleus of the peak in the radial distribution plot
29
what is psi (trident)
the wave function
30
what is the angular momentum quantum number related to (L)
the shape of the orbital
31
what is the major consequence of the exclusion principle
an atomic orbital can hold a maximum of two electrons and they must have opposing spins
32
what does penetration do
it increases the average effective nuclear charge for its electron and it decreases the shielding of a 2s electron by the 1s electrons
33
what does each solution to shrodingers equation give
an energy state associated with a given atomic orbital
34
:(
:(
35
what do transition metals lose first s or d electrons
s
36
what species are paramagnetic and what do they do
they are species with 1 or more unpaired electrons; they are attracted by an external magnetic field
37
elements in the same group have similar _______ and similar patterns of _______
valence electron configurations and reactivity
38
what are diamagnetic species and what do they do
they are species with all electrons paired, they are slightly repelled by an external magnetic field
39
are cations larger or smaller than parent atoms
smaller
40
are anions larger or smaller than parent atoms
larger
41
what do main group s block metals do
lose all electrons with the highest n balue
42
where do non metals gain electrons
in the p orbitals of the highest n value
43
what is penetration
the process by which an outer electron moves through the region occupied by the outer electrons to spend part of its time closer to the nucleus
44
what is the exclusion principle
no two electrons in the same atom can have the same four quantum numbers
45
which electrons are removed first from main group metals p or s
p
46
what does metallic behavior do across a period and down a group
in increases from right to left and down
47
what do elements that have low IEs and less negative EAs tend to do
lose electrons easily but attract them weakly
48
t/f elements that have high IEs and highly negative EAs tend to lose electrons with difficulty and attract them strongly
T
49
what does ionization energy do down a group? across a period?
decreases, increases
50
why does IE increase the more electrons you pull away
you are pulling electrons from a more and more positive ion
51
t/f ie2> ie1
t ALWAYS
52
what is ionization energy
the energy required to completely remove 1 mol of electrons from 1 mol of gaseous atoms or ions
53
as period number increases what happens to zeff
it rises significantly
54
which element is the biggest? the smallest?
Fr, F
55
what happens as zeff increases
outer electrons are pulled closer to the nucleus
56
what is bond energy
the energy needed to overcome the attraction between the nuclei and shared electrons, it is defined as the standard enthalpy change for breaking the bond in x mol of gaseous molecules
57
what is bond order
number of electron pairs being shared by a given pair of atoms
58
where is is the greater electron density in a covalent bond
between the nuclei
59
what causes a covalent bond
the balance between nuclei attracting the electrons and the electrons and nuclei repelling each other
60
what is the main way atoms interact
sharing electrons
61
why do ionic compounds have high mp and bp
large amounts of energy are required to free ions from their positions and separate them
62
when do ionic compounds conduct electricity
when melted or dissociated where ions can move and carry a current
63
what are typical physical behaviours of ionic compounds and why do they have these behaviours
they are hard (they do not dent), brittle (crack without deforming), and they are rigid (do not bend). there are strong attractive forces holding ions in specific positions
64
what does delta H lattice =
(cation charge * anion charge)/(cation radius + anion radius)
65
lattice energy is __________ to electrostatic energy
directly proportional
66
t/f there are periodic trends in lattice energy
t
67
what is lattice energy
the enthalpy change that accompanies the reverse of the equation of formation
68
is energy absorbed or released during electron transfer
absorbed
69
what form of matter are ionic compounds typically
solid
70
do 100% ionic or covalent bonds exist?
no, gradations of each type of bond occur
71
72
are electrons in metallic bonding localized or delocalized
deloacalized, they move freely throughout the piece of metal
73
in metallic bonding what is the metal iron core comprised of
nucleus plus inner electrons
74
what happens during metallic bonding
the enormous number of atoms in a sample of metal “pool” their valence electrons into a “sea” of electrons between and around each metal ion core
75
how does covalent bonding occur
the nucleus of each atom attracts the valence electrons of the other, drawing the atoms together
76
where does covalent bonding commonly occur
between non-metal atoms
77
what occurs during ionic bonding
electron transfer
78
where does ionic bonding occur
between atoms with large differences in electronegativity (usually between groups 1/2 and 17/the top of 16
79
what are resonance structures
two or more lewis structures for a molecule that cannot be adequately depicted by a single structure
80
what is electron pair deloaclization
the process by which electron density is spread over several atoms rather than remaining between the two atoms
81
what is a resonance hybrid
the weighted average of the resonance structures of a molecule
82
what is formal charge
the hypothetical charge on an atom in a molecule or ion, equal to the number of valence electrons minus the sum of all the unshared and half of the shared electrons
83
is formal charge the same as oxidation number
no
84
what are the electron deficient atoms
Be or B
85
what are free radicals
molecular or atomic species that contain one or more unpaired electrons which typically make the species very reactive
86
what do most free radicals have
1) a central atom from an odd numbered group
2) a lone electron (this makes them paramagnetic)
87
what are expanded valence shells
valence shells can accommodate more than 8 electrons by using available d orbitals
88
when can expanded valence shells occur
only with central non-metal atoms from period 3 or higher
89
when does the bond angle not equal the ideal angle
when there are double or triple bonds, when there are different elements, or when there is a lone pair
90
what does AXmEn represent
A- central atom
X- surrounding atom
E- non-bonding valence electron groups
91
what is the difference between electron group arrangement and molecular shape
-electron group arrangement is defined by bonding and nonbonding electron groups
-molecular shape is defined but the relative positions of the nuclei which are connected by bonding groups only
92
what are metals good conductors of
electricity and thermal energy
93
why do metals dent and bend
the metal cations are able to slide past each other in the “electron-sea” and end up in new positions
94
what are alloys
mixtures that have metallic properties and consist of solid phases of two or more pure elements, a solid-solid solution or distinct intermediate phases
95
which atoms will have more stable AOs
atoms with greater effective nuclear charge
96
what is the effect of s and p orbital mixing
lower energy of the sigma 2s and anti sigma 2s
97
in general the higher bond order the _______ the bond
stronger
98
what is molecular orbital bond order
number of electrons in bonding MOs minus the number of antibonding MOs divided by 2
99
what do electrons in an antibonding molecular orbital do
destabilize the molecule
100
what is an antibonding molecular orbital
formed when wave functions are subtracted from each other decreasing the electron density between the nuclei and leaving a node
101
what is MO theory
molecular orbital theory; describes a molecule as a collection of nuclei and electrons in which the electrons occupy orbitals extending over the entire molecule
102
where do pi bonds occur
side to side overlap
103
where do sigma bonds occur
end to end overlap
104
when does hybridization not apply
to large non metal hydrides
105
what shape does sp3d2 apply to
octahedral
106
what shape does sp3d apply to
trigonal bipyramidal
107
what shape does sp3 apply to
tetrahedral
108
what shape does sp2 apply to
trigonal planar
109
what shape does sp apply to
linear
110
what are properties of gasses
they are highly compressible, thermally expandable, they have low viscosity and density, and they are infinitely miscible
111
what are properties of an ideal gas
they have, negligible particle volume, many particles in random motion, particles colliding with each other and container walls, particles experience non interparticle forces, and the average kinetic energy of particles is directly proportional to the temperature of the gas
112
what is urms
root mean squared speed equals the square root of u bar squared
113
what does u bar squared equal
3RT/M
114
do gasses really move at typical speed in bulk
no, individual particles are moving in all different directions, they collide with each other and change direction which slows them down
115
what does temperature measure
the degree of random motion in a gas
116
does temp have meaning for one particle
no it is a statistical measure and thus only meaningful for large numbers of particles
117
what happens when we have 0 temperature
all translational motion ceases, however rotation and vibration can occur
118
what conditions do we see ideal and non ideal behaviour of gases
ideal: low p high t
non-ideal: high p low t
119
what causes non-ideal gases?
interparticle attraction
120
what does P =
nRT/(V-nb) - a(n/v)^2
121
in the van der waals equation what is a proportional to and b proportional to
a- interparticle forces
b- particle volume
122
what do particles look like in a gas?
particles are far apart and moving randomly
123
what do particles look like in a solid
they are close together and in an ordered arrangement
124
what do particles look like in a liquid
they are close together but randomly oriwnted
125
when we go from s-l-g energy is _____
what about g-l-s?
s-l-g: absorbed
g-l-s: released
126
what is sublimation
solid to gas - delta H subl
127
what is vaporization
liquid to gas - delta H vap
128
what is fusion
melting, solid to liquid, delta Hfus
129
what is condensation
gas to liquid- negative delta H vap
130
what is freezing
liquid to solid, negative delta H fus
131
what is deposition
gas to solid, negative delta H subl
132
what does the magnitude of delta H reflect
the strength of interparticle forces
133
why is delta H fus much less than delta H vap in general
much more energy needs to be absorbed to disrupt the IMFs and to separate particles far apart going from liquid to gas
134
when are phase changes reversible
in closed systems where they are equilibrium processes
135
when are phase changes not reversible
in open systems
136
what is the vapour pressure of a liquid
the constant pressure at the dynamic equilibrium where the rate of vaporization matches the rate of condensation
137
what does vapour pressure depend on
the type of liquid and the temperature
138
why does higher temperature increase vapour pressure
more particles move faster exceeding the threshold speed to escape into gas phase
139
what do substances with weaker intermolecular forces in the liquid have
higher vapour pressures and low boiling points
140
when does boiling occur
when the vapour pressure equals the external pressure
141
what is the normal boiling point
the temperature at which the vapour pressure is 1 atm
142
why does pressure have little effect on melting points
solids and liquids are nearly incompressible
143
what is happening at the melting point
a dynamic equilibrium between solid and liquid phases
144
when will a solid sublime
when IMFs are too weak to keep particles together when they leave the solid
145
what is present at the triple point
solid liquid and gas
146
what is a supercritical fluid
occurs starting at the critical point, it is when the densities of liquid and gas become equal- we cannot distinguish between them
147
is a supercritical fluid a mixture of solid and gas
NO
148
what do intermolecular forces influence
the physical properties of a substance
149
where are there no molecules
in simple ionic solids and extended network solids
150
what are interparticle forces primarily based on
electrostatic attractions
151
what is generally the strongest IMF? the weakest?
strongest- ion dipole
weakest- london dispersion (induced dipole dipole)
152
why are ion dipoles strong
they have a full ion charge involved
153
where do ion dipole forces arise
between ions and nearby polar molecules
154
where do dipole dipole forces arise
between polar molecules, where dipoles are aligned to maximize attractions
155
where do hydrogen bonding forces occur
between molecules that have H bonded to NOF
156
why are hydrogen bonds strong
1) the difference in electronegativity is particularly large for N-H O-H and F-H
2) hydrogen is a small atom which allows the close approach of other dipoles
157
what produces an induced dipole
shifts in electric field strength often produced by shifts in electron density
158
when do induced dipole induced dipole forces arise
between non polar molecules or single atoms
159
what is polarizability
the ease with which the electron cloud can be distorted to create a charge separation
160
what increases polarizability
greater number of electrons and larger molecule size
161
which is more polarizable cations or anions
anions because they have more electrons
162
polarizability _______ down a group and _______ across a period
increases down a group and decreases across a period
163
what does surface tension refer to
the resistance of a liquid to increase its surface area
164
what does high surface tension imply
strong intermolecular forces
165
what does capillarity refer to
the rising of liquid in a tube
166
what is wetting
the spreading of a liquid across a surface
167
what are cohesive forces
the forces within a liquid
168
what are adhesive forces
the forces between the liquid and the tube or surface
169
what happens to a liquid in a tube when cohesive and adhesive forces are similar in strength and character? different?
similar: the liquid is drawn up the tube
different: the liquid is not attracted to the tube
170
what is viscosity
the resistance of a liquid to flow
171
what does a high viscosity imply
high IMFs
172
what happens to viscosity of a motor when temperature increases
the viscosity decreases as HC carbon chains are disentangled
173
in XW30 what does a higher X value imply
more viscous oil
174
what is the solute
the minor component
175
what is the solvent
major component
176
what is a good guideline for solubility
“like dissolves like”
177
which electrons are involved in forming compounds
valence electrons
178
what are outer electrons
those in the highest energy shell, they spend most of their time furthest from the nucleus
179
what are core electrons
those that an atom has in common with the previous noble gas and any completed transition series, they fill all lower-energy shells of an atom
180
what are half filled and filled sub shells
unexpectedly stable
181
which subshell is more staple 2s or 2p
2s, it penetrates closer to the nucleus
182
what does a lower nuclear charge do
makes the electron easier to remove
183
what does shielding do
it reduces the full nuclear charge to an effective nuclear charge
184
what are the two types of shielding
1) shielding by other electrons in a given shell
2) shielding by electrons in inner shells
185
what are the two types of shielding
1) shielding by other electrons in a given shell
2) shielding by electrons in inner shells
186
how many possible orientations does a d orbital have
5
187
what is a 90% probability contour
the shape that the electron is within 90% of the time
188
how well can an electrons position be known
with a certain probability
189
as _______ increases, the probability that outer electrons spend most of their time farther from the nucleus increases
size
190
as we move down a group what happens
n dominates and increases
191
why does shielding occur
each electron feels both attraction to the nucleus and repulsion from other electrons, those repulsions counteract the nuclear attraction to a degree
192
what are lobes
regions where it is highly probable to find an electron
193
can we assign a definite size to an atom
no, the probability of finding an electron anywhere away from the nucleus is never 0
194
what is the trident squared
probability density, a measure of the probability of finding the electron in some tiny volume of the atom
195
what does removing an electron require
energy to overcome electrostatic attraction, IE is always positive
196
what is electronegativity
the ability of an atom in a bond to attract electron density towards itself
197
what is black body radiation
light given off by a hot idealized object that absorbed all of the radiation incident on it
198
what is the lowest possible energy of a d subshell
3d
199
the energy of an atom is quantized meaning?
it occurs in fixed quantities rather than being continuous
200
what is an electron density diagram
an electron-cloud depicition
201
what is the p orbital
the dumbbell or peanut shaped orbital
202
what does the fourth quantum number describe (ms)
spin
203
by convention what is the spin assigned to the first electron orbital
+1/2
204
what is the s orbital
the spherical shaped orbital
205
where does probability peak at (electron location)
near, but not at the nucleus
206
what is a quantum
the definite amount of energy an atoms absorbs/emits when changing energy levels
207
what is an orbital
a mathematical function that describes the electrons matter-wave (the three-dimensional space in which the highest probability exists of finding an electron)
208
why do electrons have certain allowable energies and frequencies
because electrons have wave-length motion in orbitals of fixed radii
209
what does the magnetic quantum number prescribe
the 3-D orientation of the orbital in the space around the nucleus
210
what is electron affinity
the energy change accompanying the addition of 1 mol of electrons to 1 mol of gaseous atoms or ions
211
what is urms =
sqrt(3RT/M)
