Week 8 Flashcards
constructive interference
occurs in regions where peaks or troughs for the 2 waves coincide
destructive interference
occurs in regions where the peak of one wave coincides with trough
amplitudes of interfering waves add together and produce a…
resultant wave
diffraction
wen a wave encounters an obstacle, the wave appears to bend around a small obstacle or spread out in semicircles
light shows properties of ____ and ____
particles- through photoelectric effect
waves- through light diffractions and interferences
energy levels of the hydrogen atom are given by equation
En= -2.179*10^-18(J/n^2)
De Broglie Wavelength (predicted that a particle with mass m and velocity v should also exhibit the behavior of a wave given by..)
wavelength=h/mv
wavefunction
mathematical description of an atomic orbital that describes the shape of the orbital, it can used to calculate the probability of finding the electron at any given location in the orbital as well as dynamical variables such as the energy and the angular momentum
interpretation of the wavefuntion
electrons are still particles, and so the wave represented by wavefunction variable aren’t physical waves, when you square them you obtain probability density which describes probability of the quantum particle being present near a certain location in space
wavefunction can be used to determine
the distribution of the electrons density with respect to the nucleus in an atom (but cannot be used to pinpoint exact location of the electron at any given time)
electrons can exists…
only on discrete energy levels but not in-between them, meaning the energy of an electron in an atom in quantized
principle quantum number variable
energy levels are labeled with an n value where n= 1 to infinity (energy levels of an atoms are greater with the greater value of n)
principle quantum number
defines the location of the energy level, similar concept as n in Bohr’s model of shell number the further from the nucleus the higher the shell number the higher the energy level
deltaE= Efinal-Einitial= -2.179*10^-18(1/nf^2 - 1/ni^2)
deltaE= Efinal-Einitial= -2.179*10^-18(1/nf^2 - 1/ni^2)
atomic orbital
a general region in an atom within which an electron is most probable to reside
angular momentum quantum number
(l) integer defines the shape of the orbital, l=0,1,2.. n-1 (if n=1 only one value of l=0; if n=2 whereas l=1, 0)
orbitals with the same value of l
will form a subshell
angular momentum is
a vector, electrons with this can have this momentum oriented in different directions
magnetic quantum number
(ml), specifies the z component of the angular momentum, the orbital orientation (-l to l, if l=1 ml= -1,0,1)
orbital abbreviations
l=0 s orbital
l=1 p orbital
l=2 d orbital
l=3 f orbital
orbitals
mathematically derived regions of space with different probabilities of electrons in them
interpretation of wavefunctions (orbitals)
probability density of finding an electron at a given point in space [wavefunction(r)]^2
dot density diagram
higher density of black dots, higher probability of finding electrons
radical probability
probability of finding a 1s electron at a distance r from the radius
-calc by adding probability of an electron being at all points ona series of x spherical shells of radius r1, r2, r3, rx-1, rx
electron probability density greatest at
r=0
surface area of each spherical is equal to
4(pi)r^2
boundary surface plot
spherical shaped plot constructed by drawing a circle or sphere around a large percentage (75-90ish) of the dots
s orbitals in n=2, 3… however look a little different
-the electron probability density doesn’t fall off smoothly with increasing r
-series of minima and maxima are observed (corresponds to radical nodes)
nodes
points with 0 amplitude
-number of radical nodes in an orbital is n-l-1
3 things happen to s orbitals as n increases
- they become larger extending farther from the nucleus
- they contain more nodes, similar to standing wave that has regions of significant amplitude separated by nodes
- for given atom, s orbitals also become higher in energy as n increases because of the increased distance from the nucleus
p orbital
-3D model with x, y and axis
-because 2p subshell has l=1, with ml(-1,0,1) there are 3 2p orbitals
only ___ orbitals are symmetrical
s
as l increases, the number of orbitals in given subshell
increases and shapes become more complex
d orbitals
subshells with l=2 have 5d orbitals, the first shell to have a d subshell is n=3
f orbitals
principle shells with n=4 can have subshells with l=3 ad ml values of -3,-2,-1,0,1,2,3; subshells consist of 7 f orbitals
orbital energies
depend only on principle quantum number(n)- energies of 2s, 2p, and 2d are all equal
spin quantum number
(ms) complete quantum phenomenon with no reaction to other quantum numbers and can’t be derived from solving Schrodinger’s equations, describes an intrinsic electron “rotation” or “spinning” [alpha state- spin up, beta state- spin down] ms value = +-1/2
magnet has lower energy if its magnetic momentum is aligned witht he external magnet field and higher is opposite to applied field
this is why ms +1/2 has slightly lower energy in an external field in positive z direction than ms+-1/2
Pauli Exclusion Principle
no 2 electrons in the same atom can have exactly the same set of all 4 quantum numbers (can share n,l,ml only if ms have different values and because ms can only be +-1/2 any atomic orbital can be populated by only 0, 1 or 2 electrons
black body radiation
radiation(light) given off by hot bodies, the intensity is a function of wavelength, distribution is a function of the temperature
quantized
positions that are fixed and can’t be in between 2 points
continuous
positions that can be anywhere on a spectrum
is energy absorbed or released when an electron goes from n=4 energy level to n=2 energy level
released, down arrow=energy releasing (up arrow is absorbing energy)
rydberg equation energy of a photon
2.179(or J given from atom being used)*10^-18((1/nf^2)-(1/ni^2))
what is the color of this photon equation
E=hc/wavelength
should electromagnetic radiation be described as a wave or a particle
evidence that its a wave: undergoes diffraction
evidence that its a particle: photoelectric effect, blackbody radiation
in a spectrum summary (chart with lines pointing up and down showing electrons going from one state to another)
the smallest energy change is the longest wavelength
wave-particle duality equation
wavelength= plancks constant/ mass * velocity
electrons are described by wave functions… Schrodinger’s equation allows for the calculation of
-the energy levels available for the electrons in an atom
-the probability of finding an electron at a particular place in an atom
results of the equation
-electrons are found in atomic orbitals
-the exact location of an electron can never be pinpointed, but the probability of an electron being in a particular location can be calculated