1
Q
alchemy
A
attempts to turn cheap metals into gold
2
Q
dalton’s atomic theory
A
- each element is made up of tiny particles called atoms
- the atoms of a given element are identical
- chemical compounds are formed when atoms combine with each other
- chemical reactions involve reorganization of the atoms - changes in the way they are bound together. the atoms themselves are not changed
3
Q
activated complex
A
transitional state where bonds break and form
4
Q
JJ Thomson
A
- postulated the existence of electrons using a cathode ray tube
- the electrons shifted towards the positive
5
Q
ernest rutherford
A
explained the nuclear atom, containing a dencse nucleus with electrons traveling around the nucleus at a large distance
6
Q
nucleons
A
protons and neutrons
7
Q
the nucleus is:
A
small compared with the overall size of the atom
extremely dense; accounts for almost all of the atom’s mass
8
Q
what makes the atom so large
A
even though the nucleus is relatively small, the electron cloud gives the atom its largeness
9
Q
the mass and charge of an electron
A
mass = 9.11 * 10^-31kg
charge = -1
10
Q
the mass and charge of proton
A
mass = 1.67 * 10^-27 kg
charge = +1
11
Q
the mass and charge of a neutron
A
mass = 1.67 * 10^-27 kg
charge = 0
12
Q
law of conservation of mass
A
mass is neither created nor destroyed
13
Q
law of definite proportion
A
a given compound always contains exactly the same proportion of elements by mass
14
Q
law of multiple proportions
A
when two elements form a series of compounds, the ratios of the masses of the second element that combine with 1 gram of the first element can always be reduced to small whole numbers
15
Q
avogadros hypothesis
A
at the same temperature and pressure, equal volumes of different gases contain the same number of particles
16
Q
periodic table: 1A
A
alkali metals
17
Q
periodic table: 2A
A
alkaline earth metals
18
Q
p-block elements
A
19
Q
properties of metals
A
- efficient conductors of heat and electricity
- malleable (can be hammered into thin sheets)
- ductile (can be pulled into wires)
- lustrous (shiny)
- tend to lose electrons and form cations “+” charged
20
Q
properties of metalloids
A
- substances with the properties of both metals and nonmetals
- AKA semimetals
- B, Si, Ge, As, Sb, Te
21
Q
properties of nonmetals
A
- nonconductors of heat and electrcity (insulators)
- not malleable, but are brittle
- not ductile
- dull and without a luster
- tend to gain electrons to form anions
H, He, N, O, S, & P
22
Q
quicklime
A
calcium oxide
23
Q
epsom salts
A
magnesium sulfate
24
Q
milk of magnesia
A
magnesium hydroxide
25
laughing gas
dinitrogen monoxide
26
electromagnetic radiation
radiant energy that exhibits wavelength like behavior and travels through space at the speed of light in a vacuum
27
as wavelength increases what happens to frequency
decreases
28
what is the highpoint of a wave called
crest
29
what is the lowpoint of a wave called
trough
30
wavelength (lambda)
distance between two peaks in a wave
31
frequency (curvy v - nu)
number of waves per second that pass a given point in space
32
speed (c)
speed of light is 2.9979 * 10^8 m/s
33
wavelength and frequency have an indirect relationship
c = ν λ
**higher the frequency, lower the wavelength and vice versa
34
quantized energy
35
dual nature of light
36
quantization of energy
an object can gain or lose energy by absorbing or emitting radiant energy in QUANTA
37
quantum
smallest possible increment of energy gained/lost
38
ΔE = hv = hc/λ
ΔE = change in energy
h = planck's constant, 6.626 * 10^-34 Js or Kgm^2/s^2
v = frequency, in s^-1
λ = wavelength, in m
39
photoelectric effect
- suggested that ER can be viewed as a stream of particles called photons
- particle nature of light
- higher the frequency, higher the energy, lower the wavelength
- lower the frequency, lower the energy, higher the wavelength
40
binding energy
41
mass of a photon at rest is
0
42
energy of a photon
E = hc/λ
43
mass of photon
m = h/λc
^^formula used to calculate mass of ER
44
de Broglie's equation
λ = h/mv
λ = wavelength in m
h = 6.626 * 10^-34kgm^2s^-1
m = kg
v = m/s
45
continuous spectrum
contains all wavelengths
46
line spectrum
shows only certain wavelengths
47
visible light
causes electronic transitions
48
infrared
causes molecular vibrations
49
microwaves
cause molecular rotation
50
balmer series
visible lines in H atom spectrum are called the balmer series
51
ground state
the lowest possible energy state for an atom (n=1)
52
where are the higher energy electrons in an atom? how easily removable are they?
they are in outer shells and are easier to remove because they are more shielded from the positive nucleus by inner shell electrons
53
quantum model for the hydrogen atom
- the electron in a hydrogen atom moves around the nucleus in certain allowed circular orbits
- tendency of the revolving electrons to fly off the atom can be balanced by its attraction to the positively charged nucleus
54
angular momentum
mass * velocity * orbital radius
55
energy changes in the hydrogen atom
ΔE = Efinal state − Einitial state
56
E = -2.178 * 10^-18 J (z^2/n^2)
E = energy of the levels in the H-atom
z = nuclear charge (for H = 1)
n = an integer
E becomes more negative as electrons move closer to the nucleus
57
heisenburg uncertainty principle
- cannot simulataneously define the position and momentum (m*v) of an electron
58
principle quantum number (n)
- related to the size and energy of an orbital
- as the value of n increases: orbital becomes larger, electron spends more time away from nucleus, energy increases since electron is less tightly bound, energy is less negative
59
quantum numbers (QN)
1. prinicipal QN
2. angular momentum QN
3. magnetic QN
4. electron spin QN
60
quatum number: principal QN
n = 1, 2, 3
related to the size and energy of the orbital
61
quatum number: angular momentum QN
l = 0 to n-1
- relates to shape of the orbital
s = 0
p = 1
...
62
quatum number: magnetic QN
ml = +l to -l
- relates to orientation of the orbital in space relative to other orbitals
63
quatum number: electron spin QN
+1/2, -1/2
- relates to spin states of the electrons
64
when asked all possible QN for 3rd shell
write 3s2, 3p6, 3d10
65
when writing the ion of an element, always remove form the LAST shell, even if it comes before another sublevel
66
pauli exclusion principle
in a given atom no two electrons can have the same set of all four quantum numbers (n, l, ml, ms)
- therefore, an orbital can hold only two electrons, and they must have opposite spins
67
aufbau principle
- as protons are added one by one to the nucleus to build up the elements, electrons are similarly added to these hydrogen-like orbitals
68
hund's rule
- the lowest energy configuration for an atom is the one having the maximum number of unpaired electrons allowed by the Pauli principle in a particular set of degenerate orbitals
**think about how we distribute one arrow to all orbitals before doubling up
69
valence electrons
the electrons in the outermost principle quantum level of an atom
70
core electrons
inner electrons
71
arangement of electrons in atoms
shells (n) -> subshells (l) -> orbitals (ml)
72
effective nuclear charge (Z*)
Z* is the nuclear charge experienced by the outermost electrons.
- increases across a period owing to incomplete shielding by inner electrons
73
coulombs law
- an electron in a given shell requires a certain energy to be separated from the atom
- an electron can be said to occupy an energy level in an atom
- the energy levels corresponding to these shells are quantized (only discreet energy levels should be found)
74
PES
photoelectron spectroscopy
- this method uses a photon (a packet of light energy) to knock an electron out of an atom
- works by bombarding electrons with high energy x-rays or ultraviolet light to eject electrons from the surface
75
higher the nuclear charge the greater the binding energy
76
PES: core electrons
- core electrons like 1s electrons are closer to the nucleus and take much more energy to remove
77
ionization/binding energy
78
what causes the gap in a photoelectron spectrum
the gap in the energy axis due to the shielding effect
79
why does the size go up when going down a group
because more PEL are occupied
- additional PEL's increase the shielding or screening effects
80
why does the size go down when going across the period
- binding energy increases
- more effective nuclear charge
81
atomic radii
obtained by measuring the distance between atoms in a chemical compound
82
covalent atomic radii
determined from the distances between atoms in covalent bonds
83
metallic radii
obtained from half the distance between metal atoms in solid metals crystals
84
increased electron repulsion leads to a bigger electron cloud
85
does the size go up or down when gaining an electron to form an anion
anions are LARGER than the atoms from which they come
- electron/proton attraction has gone down so size INCREASES
- gained electron increases the e- repulsions which increase the radii
86
does the size go up or down when losing an electron to form a cation
- cations are smaller than the atoms from which they come
- the electron/proton attraction has gone UP and so size decreases
- loses a valence shell
87
ionization energy
energy required to remove an electron from an atom in the gas phase
88
why does IE increase across a period
because Z* increases as electrons added in the same principal quantum level do not completely shield the increasing nuclear charge caused by the added protons
89
why are metals good reducing agents
because they get oxidized faster
90
electron affinity
- a few elements gain electrons to form anions
- the energy involved when an anion loses an electron
- as we go across a period from left to right, electron affinities become more negative (increases)
91
what is an indicator of a solutions concentration
the intensity of color (darker = more intensity)
92
spectrophotometry
the intensity of color can be given a numerical value by comparing the amount of light prior to passing it through the sample and after passing through the sample
- measurements are the transmittance and absorbance
93
beer-lambert law
the linear relationship between absorbance and concentration of an absorbing species
94
beer lambert law formula
A = abc
A is the absorbance
"a" is molar absorptivity in L/[(mole)(cm)]
"b" is the path length in cm
"c" is the concentration of the analyte (sample) in mol/L
95
b or path length in beers law becomes a constant
when the same cuvette is used for all samples
96
working curve
is produced by plotting the absorbance vs concentration
- helps determine the concentration of an unknown sample by knowing the absorption
97
transmittance vs absorbance: optimal wavelength =
maximum absorbance
98
proportionality
beers law tells us that absorption is proportional to concentration therefore
A1/A2 = C1/C2
99
the specific nature of the interaction between matter and light
depends on a compounds molecular structure
100
what does spectrophotometry describe
it describes either the transmittance or absorbance of light by a substance
101
