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Chemistry Chapter 7 Homework Assignment

Terms in this set (27)

What is the threshold frequency ν0 of cesium?
Note that 1 eV (electron volt)=1.60×10−19 J.
ν0 =
9.39×1014
Hz
A ray of red light has a wavelength of about 7.0×10−7 m. Will exposure to red light cause electrons to be emitted from cesium?
no
What is the kinetic energy of the emitted electrons when cesium is exposed to UV rays of frequency 1.4×1015Hz?
Express your answer in joules to three significant figures.
KE =
3.06×10−19
J
Electromagnetic radiation behaves both as particles (called photons) and as waves. Wavelength (λ) and frequency (ν) are related according to the equation
c=λ×ν
where c is the speed of light (3.00×108 m/s). The energy (E in joules) contained in one quantum of electromagnetic radiation is described by the equation
E=h×ν
where h is Planck's constant (6.626×10−34 J⋅s). Note that frequency has units of inverse seconds (s−1), which are more commonly expressed as hertz (Hz).
A microwave oven operates at 2.10 GHz . What is the wavelength of the radiation produced by this appliance?
Express the wavelength numerically in nanometers.
λ =
1.43×108
nm
Two of the types of infrared light, IR-C and IR-A, are both components of sunlight. Their wavelengths range from 3000 to 1,000,000 nm for IR-C and from 700 to 1400 nm for IR-A. Compare the energy of microwaves, IR-C, and IR-A.
Rank from greatest to least energy per photon. To rank items as equivalent, overlap them.
Greatest energy
IR-A
IR-C
Microwaves
Least energy
A radio station's channel, such as 100.7 FM or 92.3 FM, is actually its frequency in megahertz (MHz), where 1MHz=106Hz and 1Hz=1s−1.
Calculate the broadcast wavelength of the radio station 103.5 FM.
Express your answer to four significant figures and include the appropriate units.
λ =
2.897 m
Green light has a frequency of about 6.00×1014s−1. What is the energy of a photon of green light?
Express your answer to three significant figures and include the appropriate units.
Ephoton =
3.98×10−19 J
Hospital X-ray generators emit X-rays with wavelength of about 15.0 nanometers (nm), where 1nm=10−9m. What is the energy of a photon of the X-rays?
Express your answer to three significant figures and include the appropriate units.
Ephoton =
1.32×10−17 J
Sort the following transitions from an excited state to a ground state according to the series into which they fall.
Drag the appropriate transitions to their respective bins.
Paschen series
n=4 to n=3

Balmer series
n=7 to n=2
n=5 to n=2
n=3 to n=2

Lyman series
n=7 to n=1
n=5 to n=1
Calculate the energy difference for a transition in the Paschen series for a transition from the higher energy shell n=6.
Express your answer to four significant figures and include the appropriate units.
−1.816×10−19 J
Calculate the wavelength of the photon emitted when an electron makes a transition from n=6 to n=3. You can make use of the following constants:
h=6.626×10−34 J⋅s
c=2.998×108 m/s
1 m=109 nm
Express your answer to four significant figures and include the appropriate units.
λ =
1094 nm
What is the only possible value of mℓ for an electron in an s orbital?
Express your answer numerically.
0
What are the possible values of mℓ for an electron in a d orbital?
Express your answer numerically with sequential values separated by commas.
-2,-1,0,1,2
Which of the following set of quantum numbers (ordered n, ℓ, mℓ, ms) are possible for an electron in an atom?
Check all that apply.
4, 3, -2, 1/2
4, 2, -2, 1/2
2, 1, 0, 1/2
How much energy does the electron have initially in the n=4 excited state?
Express your answer with the appropriate units.
En =
−1.37×10−19 J
What is the change in energy if the electron from Part A now drops to the ground state?
Express your answer with the appropriate units.
ΔE =
−2.05×10−18 J
What is the wavelength λ of the photon that has been released in Part B?
Express your answer with the appropriate units.
λ =
9.70×10−8 m
What might the photon from Part C be useful for?
getting a suntan
What is the azimuthal quantum number (also called the angular-momentum quantum number), ℓ, for the orbital shown here?
ℓ= 2
What is the label for the orbital shown here that indicates the type of orbital and its orientation in space?
dyz
Compare the orbital shown in Parts A and B to the orbital shown here in size, shape, and orientation.
mℓ only
How would the dx2−y2 orbital in the n=5 shell compare to the dx2−y2 orbital in the n=3 subshell?
A. The contour of the orbital would extend further out along the x and y axes.
B. The value of ℓ would increase by 2.
C. The radial probability function would include two more nodes.
D. The orientation of the orbital would be rotated 45∘ along the xy plane.
E. The mℓ value would be the same.
Drag the appropriate items to their respective bins.
True
A C E
False
B D
The s orbital is spherical (nondirectional) because
Check all that apply.
- at a particular distance from the nucleus, the electron probability is the same in all directions.
-the angular wave function of an s orbital is defined by the quantum number ℓ.
-the angular wave function for all s orbitals is a constant.
The 2p orbital is not spherically symmetric because
Check all that apply.
-there are angular nodes in the yz, xz, and xy planes.
-the value of ψ2 is zero at the nucleus.
-the angular wave function of the 2p orbital depends on the values of θ and ϕ.
A three-dimensional plot of the wave function squared (ψ2) produces a diagram showing the probability density for an electron as a function of distance from the nucleus. These solutions are called orbitals.
Three solutions to ψ2 are plotted here. Identify the orbital shown in each plot.
Identify the atomic orbitals by dragging the appropriate labels to their respective targets.
red p orbital
blue s orbital
yellow d orbital
The probability of finding an electron at a point in an atom is referred to as the probability density (ψ2). The spatial distribution of these densities can be derived from the radial wave function R(r) and angular wave function Y(θ,ϕ), then solving the Schrödinger equation for a specific set of quantum numbers.
Which of the following statements about nodes and probability density are accurate?
Select all that apply.
-The probability of finding an electron at the center of a p orbital is zero.
-The 3p orbitals have two nodes.
-The 4f orbitals have three nodes.
The probability of finding an electron anywhere in a spherical radius of r is called the radial probability distribution. The shape of the plot depends on the principal quantum number (n) and the azimuthal quantum number (ℓ) for an orbital. As n increases for each value of ℓ, the number of nodes in the plot increases by one. To understand the radial distribution function for different orbitals, match the orbital that corresponds to the radial distribution function shown in each plot.
2p
3p
3d
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