Chapter 8 The Quantum Mechanical Model of the Atom Flashcards
Until the beginning of the twentieth century it was
believed that all physical phenomena were what?
deterministic
Final state could be determined from the initial state
deterministic
the present condition does not determine the future condition
indeterministic
describes the behavior of subatomic
particles.
Quantum mechanics
key point of quantum mechanics
Explaining the periodic table
– The behavior of the elements in chemical
bonding
– Provides the practical basis for lasers,
computers, and countless other applications
are incredibly small particles.
electrons
what determines the properties of atoms.
Electron behavior
a form of electromagnetic radiation
Light
Composed of perpendicular oscillating waves, one for the
electric field and one for the magnetic field
Light
is a region where an electrically
charged particle experiences a force.
electric field
is a region where a magnetized
particle experiences a force.
magnetic field
is the height of the wave.
amplitude
The distance from node to crest or node to trough (or valley)
amplitude
The amplitude is a measure of what?
light intensity
is a measure of the distance covered by the wave.
wavelength
The distance from one crest to the next
wavelength
what determines the color of light
the wavelength
is the number of waves that
pass a point in a given period of time.
frequency
how do you find out how long a cycle is?
number of waves
what is the units of frequency?
hertz
is proportional to the amplitude of
the waves and the frequency.
total energy
the larger the what the more force/energy in the wave
amplitude
or
frequently the waves strike a particular point
The color of light is determined by its
wavelength (or frequency).
is composed of light of
several wavelengths:
white light
All the wavelengths of light comprise the
electromagnetic spectrum
have the lowest energy
Radio waves
have the highest energy.
– Gamma rays
what kind of wavelengths of light have higher energy
(higher frequency).
shoter
The interaction between waves is called
interference
what kind of interference is this?
when waves interact so that they add to make a larger wave
Constructive interference
when waves interact so that they add to make a larger wave
in phase
what kind of interference is this?
when waves interact
so they cancel each other it is called
out of phase
When traveling waves encounter an obstacle or
opening in a barrier that is about the same size as
the wavelength, the waves bend around the
obstacle;
diffraction
The diffraction of light through two slits separated by a distance comparable to the wavelength results in an
interference
pattern
what is the photoelectric effect
was observed that many metals emit electrons
when a light shines on their surface.
light energy being transferred to the electron.
Classic wave theory
According to this theory, only the amplitudeof
the light (i.e. intensity) determines emission of the
electron.
Classic wave theory
was needed for electrons to be
emitted regardless of the light
intensity
minimum frequency
light intensity
threshold
frequency
light from a dim source caused
electron emission without any
lag time.
High-frequency low-intensity
packets that deliver atoms
quanta or photons
what is Planck’s constant?
6.626 ×10−34 J ∙ s.
One photon at the threshold frequency gives
the electron just enough energy for it to what?
escape the atom.
When irradiated with a what? the electron
absorbs more energy than is necessary to
escape.
shorter wavelength
photon (higher frequency),
the energy needed for a electron to escape the atom
binding energy
This excess energy becomes
kinetic energy of the ejected electron.
When atoms or molecules absorb energy, that
energy is often released as what?
light energy
When that emitted light is passed through a
prism, a pattern of particular wavelengths of
light is seen that is unique to that type of atom
or molecule – the pattern is called an
emission spectrum.
analyzed the spectrum of
hydrogen and found that it could be
described using the following mathematical
equation:
Johannes Rydberg
how the structure of atoms change when it undergoes energy transitions.
The Bohr Model of the Atom
explains absorption and emission spectra.
Bohr model of the atom
Bohr’s major idea was what?
that the energy of the atom
was quantized, and that the amount of energy in
the atom was related to the electron’s position
in the atom
means that the atom could only have very
specific amounts of energy.
Quantized
the electrons travel in orbits that are at a
fixed
distance from the nucleus.
when do electrons emit radiation?
hen they “jump”from
an orbit with higher energy down to an orbit with
lower energy.
what determines the energy of a photon?
distance between the orbits
are manifestations of the wave nature of electrons
stationary states
Electrons are never observed between what?
stationary states
proposed that particles have wave-
like properties.
Louis de Broglie
predicted that the wavelength of a
particle was inversely proportional to its
momentum.
Louis de Broglie
predicted that energy is proportional to the radius of orbit
bohr
proof that electrons had wave nature came from what?
electrons would produce an interference
pattern
Any experiment designed to observe the electron
results in detection of a single electron particle and no interference pattern.
Uncertainty Principle Demonstration
interference pattern
Wave nature
position, which slit it is passing
through (waves do not have defined positions)
Particle nature
The wave and particle nature of the electron
are
complementary properties.
stated that the product of the uncertainties in
both the position and speed of a particle was inversely proportional to its mass
Heisenberg
the more accurately you know the
position of a small particle, such as an electron, what?
the less you know about its speed, and vice versa.
particles move in a path determined by what?
particle’s velocity,
position, and forces acting on it.
definite, predictable future
Determinacy
indefinite future, can only predict
probability
indeterminacy
Because we cannot know both the what and what we cannot predict the path it will follow.
position and
velocity of an electron,
what can we find out about electrons with the information given to us?
probability an electron will be found in a particular region
Electron energy and position are what?
complementary
slide 67 on The spin quantum number specifies the
orientation of the spin of the electron.
spin up
+1/2
spin down
-1/2
it transitions from an orbital in a lower energy level to an orbital in a higher
energy level.
excited
it transitions from an orbital in a higher energy level to an orbital in a lower energy level.
relaxes
When an electron relaxes what happens?
a photon of light is released
whose energy equals the energy difference between
the orbitals.
allows us to calculate the probability of finding an electron with a particular amount of energy at a
particular location in the atom.
Schrödinger’s equation
a probability distribution map of a region where the electron is likely to be found.
orbital,
three integer terms in the wave function.
quantum numbers
what does n stand for?
Principal quantum number,
what does l mean
Angular momentum quantum number
what does ml mean?
Magnetic quantum number,
what to know ab n
on notes
determines the shape of the orbital
l
what kind of orbitals are s?
what is the number of l associated with it?
spherical
l = 0
what to know ab l
look on notes
what kind of orbitals are p?
what is the number of l associated with it?
two balloons tied at the knots.
l = 1
what kind of orbitals are d?
what is the number of l associated with it?
like four balloons tied at
the knots.
l = 2
what kind of orbitals are f?
what is the number of l associated with it?
orbitals are mainly like
eight balloons tied at the knots.
l = 3
specifies the orientation of the orbital
ml
what to know ab ml
look at notes
Orbitals with the same value of are in the
same what?
principle energy level or principle shell
Orbitals with the same values of n and l
are said to be in the same what
in the same sub level or subshell
the number of sublevels within a
level = to what?
n
the number of orbitals (ml) within a sublevel = to what?
2l + l
the number of orbitals in a level is equal to what?
n squared
specifies the orientation of the
spin of the electron. (ms)
The spin quantum number
The wavelengths of lines in the emission
spectrum of hydrogen can be predicted by what?
calculating the difference in energy between any two states.
can predict these lines very accurately
for a 1-electron system.
Bohr mechanical models
and
quantum mechanical models
The energy of a photon released is equal to
the difference in energy between the two
levels between which the electron is
transitioning.
represents the probability (per unit volume)
of finding an electron at a particular point in space.
probability density function
what we need to know ab s orbitals
look at notes
s orbital
To get a better idea of the orbital radius of the electron, we use the what?
radial distribution function.
represents the total probability of finding an
electron within a thin spherical shell at a distance r
from the nucleus.
The radial distribution function
is the net result of the radial distribution function
is a plot that
indicates the most probable
distance (r) of the electron
the shape of the radial distribution
function is the result of
multiplying
two functions with opposite trends:
decreases with increasing r.
probability density function
increases with increasing r
volume of the thin shell
2s orbital
volume of the thin shell, which is
what ? at the nucleus
zero
The Probability Density/unit volume maximum is where for the s orbital.
the nucleus
represents the total probability of finding
an electron at a certain radius from the nucleus.
The radial distribution function
where is the radial distribution function at maximum?
at the most probable radius
in the functions are where the probability drops to 0.
nodes
how many and where are the nodes in p orbital?
one and at the nuclues
where does the p orbital stand energy wise?
second lowest
n levels are d orbitals found
3 and greater
what n levels are p orbital found
2 and up
what n values are s orbitals found?
1 and up
what rank is the s orbital according the amount of energy
lowest energy
what rank is the d orbital according the amount of energy
third lowest energy
what rank is the f orbital according the amount of energy
4 and greater
what rank is the f orbital according the amount of energy
the fourth lowest
are determined from mathematical wave functions
orbitals
how are orbitals determined?
wave functions
The sign of the wave function is called its
phase
