ch4revans15­16.notebook
April 28, 2016
Ch4 Review Answers
1. A very bright line in the spectrum of sodium has a wavelength of 5.90 x 102nm. What is the frequency of this line?
2. When an electron in an atom falls from the 5th to the 2nd energy level, 4.58 x 10−19 J of energy are released. What is the frequency of the electromagnetic radiation that is emitted? Is this visible light?
3. A device emits light energy with a frequency of 9.37 x 107 Hz. What is the wavelength of this electromagnetic wave? Is the device a tanning bed, a red laser or a radio tower?
Mar 30­2:35 PM
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ch4revans15­16.notebook
April 28, 2016
4. What orbital will the 6th electron of a ground­state nitrogen atom occupy? (Hint: You should probably write the orbital diagram of nitrogen to figure this out!)
5. Write electron configurations for:
As
Sr
Pd
P
6. Write the noble gas configuration for each element in #5.
(see above)
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7. Name the element described by: 1s22s22p63s23p2. How many unpaired electrons does it have?
8. Name the element described by: 1s22s22p63s25s1
Is this element in the ground state or excited state? How can you tell?
9. Use an orbital diagram to represent the electrons in phosphorus.
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10. Light emitted in the spectrum of an element has a wavelength of 7.5 x 10­7 meters.
A. What type of light is this? (visible, infrared, or ultraviolet) It is longer wavelength than visible light (400­700 nm = 4x 10 ­7 ­ 7x10­7m)
Thus it is infrared light.
B. Calculate the amount of energy of a photon of this light.
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11. Explain the main difference between luminescence and incandescence. Give two examples of incandescent light sources. Give examples of chemiluminescence and bioluminescence. State types of spectra each emit.
Incandescence is light produced by an object heated to glowing. = continuous spectrum Luminescence is light produced without heat. (see Jeopardy game for examples) = emission (bright line) spectrum
12. Describe what is happening to electrons in an atom when light (spectrum) is emitted. What is the function of electricity or a flame in this process? What type of spectrum is emitted?
The electricity or flame excite electrons which move to a higher energy level, farther from nucleus
These would be examples of luminescence, so they would give bright line (emission) spectrum
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13. Be able to discuss sources of error and the effect of each on Ag yield for the AgNO3 lab. Be able to do all calculations associated with the lab.
Anything that adds weight to the Ag sample in
the beaker is going to give >100% yield
Anything that causes loss of product or
incomplete formation of product will give
<100% yield
14. For each of the 4 quantum numbers, know the name, symbol and what it indicates about an electron.
1st = principal = n= distance from nucleus
2nd = sublevel = shape of 3-d location of electron
3rd = orbital = orientation of orbital in x,y,z planes
15. Recognize the contributions of Bohr, deBroglie, Heisenberg, Schrodinger, Hund and Pauli in the development of the quantum model of the atom.
Bohr = Bohr model - led to QM model
deBroglie = dual wave/particle nature of electrons
Heisenberg = Uncertainty Principle - disproved Bohr
model
Hund = rule that unpaired electrons in same level
must have parallel spins to maximize stability.
Pauli = exclusion principle = two electrons in the
same atom cannot have the same 4 QNs
16. Be able to compare and contrast the Bohr and Quantum models of the atom. Compare
Contrast
Apr 28­8:52 AM
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