Download Chapter 5 Homework A - mayberryapchemistry

Chapter 5 Homework A
Element
Atomic #
Mass #
28
58
Isotope
21
10Ne
Protons
Electrons
Neutrons
Chlorine - 35
40
18
Selenium
40
11
5B
35
104
46
45
1. What is the symbol of the element that is composed of each of the following:
a. 94p, 150n, 94e
b. 79p, 118n, 76e
c. 34p, 45n, 36e
d. 52p, 76n, 54e
2. The atomic weight of lithium is 6.941 amu. The two naturally occurring isotopes
of lithium have the following masses: Lithium-6 is 6.01512 amu and Lithium-7 is
7.01600 amu. Calculate the percent abundance of each of the isotopes.
3. The atomic weight of rubidium is 85.4678 amu. The two naturally occurring
isotopes of rubidium have the following masses: Rubidum-85 is 84.9118 amu,
Rubidium-87 is 86.9092 amu. Calculate the percent abundance of each of the
isotopes.
4. Silver consists of two naturally occurring isotopes, Silver 107 which has a mass of
106.90509, and Silver 109 that has a mass of 108.9047. The atomic weight of
silver is 107.8682. What is the percent abundance of each of the isotopes?
5. What is the atomic weight of a hypothetical element that consists of the following
isotopes in the indicated relative abundances? Isotope 1 has a mass of 94.9 and
occurs 12.4% of the time, Isotope 2 has a mass of 95.9 and exists 73.6% of the
time. Isotope three has a mass of 97.9 and exists 14.0% of the time. What is the
atomic weight?
6. In a mass spectrometer they found that it has an isotope that weighs 84.9117 and
exists 72.15% of the time, and an isotope that weighs 86.9085 and exists 27.85%.
What is the average atomic mass? What is the element?
7. What is the wavelength, in meters, of radiation of the following frequencies:
a. 5.60 x 1015 s-1
b. 2.11 x 1014 s-1
c. 3.89 x 1012 s-1
8. Calculate the frequency of radiation of each of the following wavelengths
a. 8973 Angstroms
b. 492 nm
c. 4.92 cm
d. 4.55 x 10-9 cm
9. What is the energy of a photon of each of the radiations in question 7? Express
your answer in joules per photon. In which regions of the electromagnetic
spectrum do these radiations fall?
10. Excited lithium ions emit radiation at a wavelength of 670.8 nm in the visible
range of the spectrum. Calculate the frequency, the energy of a photon of this
radiation, and what color is this light?
11. During photosynthesis, chlorophyll – a absorbs light of wavelength 440 nm and
emits light of wavelength 670 nm. What is the energy available for
photosynthesis from the absorption of a mole of photons?
12. Classical music radio station KMFA in Austin broadcasts at a frequency of
89.5MHz. What is the wavelength of this signal in meters?
13. Assume that 10-17 J of light are needed by the interior of the human eye to “see”
an object. How many photons of green light (wavelength = 495 nm) are needed
to generate this minimum energy?