Radiation from the Sun

These questions cover Chapter 3 – all sections

Total point value for this assignment = 30 pts

Again a combination of correctness and completeness will be used to evaluate your responses.

1. It has been suggested that the term ozone screen would be a better phrase than ozone layer to describe ozone in the stratosphere. What are the advantages and disadvantages of each term?

2. Several oxygen species play important chemical roles in the stratosphere, including oxygen atoms, oxygen molecules, ozone molecules, and hydroxyl radicals.

Draw Lewis structures for each.

a. An oxygen atom (O)

b. An oxygen molecule (O2)

c. An ozone molecule (O3)

d. A hydroxyl radical (OH) hint: what does the term “radical” mean?

3. Consider this representation of a periodic table:

acs48763_pr0208

a. What is the group number of the shaded column?

b. What is the number of outer electrons for a neutral atom of each element of this group?

4. Describe why ozone is more reactive than oxygen gas.

5. The sensitivity of DNA in a skin cell to UV light from the Sun increases with decreasing wavelength (The longer the wave, the less damaging to DNA, and the shorter the wave, the more damaging). However, all the reports of the damage caused by UV radiation focus on UV-A and UV-B radiation, why is there no attention on the damaging effects that UV-C radiation?

6. Use Figure 3.4 to specify the region of the electromagnetic spectrum where radiation of each wavelength is found. Hint: Change each wavelength to meters before making the comparison.

eub2297x_0207.jpg

a. 2.0 cm

b. 400 nm

c. 50 m

d. 150 mm

7. Arrange these types of radiation in order of INCREASING energy per photon: gamma rays, infrared radiation, radio waves, and visible light.

8. Ultraviolet radiation is categorized as UV-A, UV-B, or UV-C.

Arrange these types in order of increasing:

a. wavelength

b. energy

c. potential for biological damage

9. Draw the Lewis structure for the following atoms:

a. magnesium

b. bromine

c. helium

10. Assuming that the octet rule applies, draw the Lewis structure for each of these molecules:

a. N2 (nitrogen gas, the major component of the atmosphere)

b. CS2 (carbon disulfide, used to kill rodents; the atoms are bonded S-C-S)

c. CCl4 (carbon tetrachloride, a substance formerly used as a cleaning agent)

11. Calculate the wavelength in meters (and nanometers) of 6.79 x 1014 Hz