Environmental Chem Chp 3 (68 CONCEPTS)
True or false: Once the production of CFCs was halted there was a dramatic decrease in the amount of stratospheric chlorine.
False
True or false: Resonance forms are different possible structures for the same species that interconvert rapidly.
False
Which of the following is the correct Lewis structure for the molecule OF2?
b
True or false: CFCs are inert, nontoxic compounds.
true
Electrons that are found in the highest energy level are called
valence
Place the steps for drawing a Lewis structure in the correct order, starting with the first step at the top of the list.
1. Count 2. Add Valence 3. Arrange Outer 4. Ensure
Calculate the velocity of a wave with a frequency of 3.5 x 10e-5 s-1 and wavelength of 5.1 x 10e8 m.
1.8 x 10e4 m/s
1 nm (nanometer) = _______.
10^-9 m
An organic compound that has the prefix hydro- (e.g., hydrocarbon) contains _____.
C-H bonds are present
Which of the following statements correctly describe the origin and uses of CFCs? Select all that apply.
CFCs are inert and nontoxic. CFCs are very chemically persistent molecules.
True or false: A substance must be radioactive in order for it to emit radiation.
False
Which of the following statements correctly describe the natural sources of chlorine? Select all that apply.
HCl is a natural form of chlorine. Natural chlorine-containing substances are water soluble. Natural sources of chlorine include seawater and volcanoes.
Select the allotrope of oxygen whose bonds can be broken by UVB radiation.
O3
Match each form of oxygen with the wavelength of UV radiation that is sufficient to break its bonds.
O3 (ozone) λ ≤ 320 nm O2 (oxygen) λ ≤ 242 nm
What is the term used to describe a condition in which a dynamic system has no net change in concentration of the major species involved?
Steady state
Which of the following factors cause an increase in ozone production? Select all that apply.
Sun directly overhead Increased intensity of UV radiation Sun closer to the Earth
Match each type of UV protection with the correct description.
Sunscreen A product that contains chemicals that absorb UV-A and UV-B radiation Sunblock A product that contains compounds like ZnO and TiO2 that physically block UV radiation
Why is the actual SPF of a sunscreen usually much lower than its reported value on the bottle?
Sunscreen is most always applied in a lower dosage than recommended.
Which of the following options correctly describe how to draw a Lewis structure for a given molecule? Select all that apply.
The A-group number of a main-group element gives the number of valence electrons. The Lewis structure includes only the valence electrons for the molecule. Each line between two atoms represents two electrons.
Which of the following statements correctly describe the factors that influence the development of skin cancer in individuals? Select all that apply.
UV-A is the form of UV radiation most strongly linked with skin cancers. People with light-colored skin are more prone to melanoma.
Resonance forms are Lewis structures that have the same relative placement of _____ but a different arrangement of _____.
atoms; electrons
Exposure to UVB radiation can cause damage to eye tissue, which can lead to _ , which are cloudy areas in the lens of the eye.
cataracts
CFCs always contain ________. (Select all that apply.)
chlorine carbon fluorine
The most significant step toward halting the depletion of the ozone layer was the call to stop the production of _____.
chlorofluorocarbons
What were the most important properties considered when designing a suitable replacement for CFCs? Select all that apply.
extreme stability flammability toxicity
A highly reactive species with one or more unpaired electrons is called a(n) _____.
free radical
of a wave is the number of wave cycles per second.
frequency
The speed of a wave is determined by multiplying the _ of the wave by its wavelength. In a vacuum all electromagnetic radiation travels at a constant speed: _m/s.
frequency 3 x 10^8
For the main-group elements (1, 2, etc.) the number of valence electrons for an element is equal to the ______ number for the element.
group
According to the relationship E = h/Wavelength energy and wavelength are _____ related. Therefore, the shorter the wavelength the _____ the energy of the radiation.
inversely; greater
A catalyst ______. (Select all that apply.)
is typically regenerated during the reaction undergoes no permanent change during a reaction
On average, the concentration of stratospheric ozone at the equator is _____ than at the poles.
lower
Energy is not continuous, but is _ , which means that it is divided into "packets" each of which contains a definite amount of energy.
quantized or discrete
A single covalent bond is indicated by:
single solid line
The maximum concentration of ozone in the atmosophere is found in the _____.
stratosphere
Some UV radiation is beneficial to humans because UV-B light stimulates the production of _______, which is important for healthy bones and immune systems.
vitamin D
Light travels through a particular type of glass at a speed of 2.2 x 10e8 m/s. Which of the following options show the correct procedure to convert this quantity to units of miles per hour (mi/hr or mph), given that 1 mile is equal to 1609 meters?
(2.2×10e8)×(3600)/1609 2.2×10e8× 3600 1609 = 4.5 × 10e8 mi hr
Place the reaction steps in order for the reaction of a CFC molecule with stratospheric ozone, starting with the first step at the top of the list.
1. CFC 2. Chlorine 3. cloo
Rank the following types of radiant energy in order of increasing frequency. Start with the radiation with the lowest frequency at the top.
1. Microwave 2. Infrared 3. Visible 4. UV
Rank the three types of UV radiation in order of increasing wavelength, starting with the shortest wavelength radiation at the top of the list.
1. UVC 2. UVB 3. UVA
Place the steps taken to reduce the depletion of the ozone layer in chronological order, starting with the first step at the top of the list.
1. United Nations 2. Vienna 3. Montreal 4. Complete
Place the following types of electromagnetic radiation in order of increasing wavelength (shortest at the top to longest at the bottom).
1. X-ray 2. UV radiation 3. Visible Light 4. IR radiation 5. Radio Waves
The danger of sunburn is greatest with the UV index is equal to ______.
15
A boron (B) atom has _ valence electrons.
3
The covalently bonded species shown has _____ shared pair(s) of electrons and _____ lone pair(s).
3; 1
Calculate the wavelength of a wave with velocity of 5.1 x 10e4 m/s and frequency of 1.1 x 10e8 s-1.
4.6 x 10^-4 m
The octet rule states that when atoms bond they may lose, gain, or share electrons in order to attain an outer level containing __ electrons
8
Atoms bond in order to fill their valence shell of electrons. Most elements strive for a total of _____ such electrons while hydrogen strives for a total of _____.
8; 2
Consider the Bohr model of an atom, in which electrons reside in energy levels, denoted as n, starting from nearby the nucleus (n = 1) to farther away from the nucleus (n = 3). Which of the following electronic transitions would result in the emission of light with the shortest wavelength?
An electron moving from the n = 3 level to n = 1.
Which of the following statements correctly describe resonance forms? Select all that apply.
An individual resonance form does not accurately represent the structure of the species. No individual resonance form actually exists. Resonance forms differ only in the arrangement of electrons.
Which compound is a CFC or chlorofluorocarbon?
B
Which coefficients are needed to balance the simplified chemical equation representing the formation of ozone? energy + a O2→ b O3
Blank 1: 3 or three Blank 2: 2 or two
ating of a sunscreen indicates the length of time a sunscreen will protect your skin from reddening/burning, relative to how long it would take without sunscreen protection.
Blank 1: SPF
Lewis structures are used to represent covalent compounds. Shared electron pairs are shown either as pairs of __ or lines and only __ electrons are shown.
Blank 1: dots Blank 2: valence or outer
Most of the radiation emitted by the Sun that reaches Earth's surface is _ radiation. Only about 8% of sunlight radiation reaching Earth is _ radiation.
Blank 1: infrared or IR Blank 2: UV or ultraviolet
Electromagnetic radiation consists of particles called _ , each of which has a discrete amount, or quantum, of energy. However, since electromagnetic radiation also has wave properties, each particle is also characterized by a specific _ and frequency.
Blank 1: photons Blank 2: wavelength or energy
The pair of electrons involved in a covalent bond is called a(n) __ electron pair, whereas the electrons not involved in bonding are called an unshared or __ pair.
Blank 1: shared or bonding Blank 2: lone, nonbonding, non-bonding, nonbonded, or non-bonded
The distance a wave travels during one cycle is called its_ . This is usually measured as the distance between two _ or two troughs.
Blank 1: wavelength Blank 2: peaks or crests
Which of the following options correctly describes how H2O and N2O can cause ozone to break down in the stratosphere?
Both species form free radicals, which react with O3 to form O2.
Which of the following options is the correct Lewis structure for the molecule N2?
C
Match each element with the correct number of valence electrons.
C - 4 Be - 2 Ne - 9 F - 7
During photosynthesis ________.
CO2 and H2O are consumed to produce stored glucose sunlight is converted into stored chemical potential energy
Match each type of formula with the correct description.
Chemical formula Shows only types and ratios of atoms present Structural formula Representation of how atoms are arranged, omitting lone pairs of electrons Lewis structure Representation of how atoms are connected, including lone pairs of electrons
Which of the following radicals are responsible for ozone depletion by CFCs? (Select all that apply.)
Cl. ClO.
Which of the following are formed on polar stratospheric clouds in the Antarctic, causing severe ozone depletion when exposed to UV light?
Cl2 HOCl
Exposure to UVB radiation stimulates the production of vitamin
D
One unit used to measure ozone concentration is the _ unit, which is equivalent to 3 × 1016 O3 molecules in a vertical column of air with a cross-section of 1 cm2.
Dobson
The ______ unit is a means of measuring ozone concentration, which is based on the intensity of UV radiation through a column of air.
Dobson
Which of the following options correctly describe the determination of ozone concentration by measuring UV radiation from the atmosphere? (Select all that apply.)
Dobson units are used to quantify the amount of ozone in a column of air. The lower the intensity of UV radiation reaching the detector, the greater the concentration of ozone in a column of air.
Which of the following statements correctly describe the general characteristics of a covalent bond? Select all that apply.
Electrons in a covalent bond are common property to both atoms that make up the bond. A covalent bond involves the attraction between the nucleus of each atom and the electrons of the other. A covalent bond involves the sharing of electrons between two atoms
Which of the following options correctly describe potential biological effects of UV radiation in addition to skin cancer? Select all that apply.
Exposure to UV radiation can cause retinal damage. Harmful UV radiation could have an effect on the carbon dioxide balance of our planet.
True or false: For an electron to "jump" from a lower energy level to a higher one, energy must be emitted by the electron.
False
Which of the following species cause ozone to break down naturally in the stratosphere? Select all that apply.
H2O N2O
Match each molecule with the correct description of its bonding.
H2O2 (connectivity is HOOH) This molecule possesses no multiple bonds. HCN This molecule possesses one triple bond. CS2 This molecule possesses two double bonds.
What type of compound is depicted in the illustration?
HCFC
Which two types of molecules are potential replacements for CFCs?
HFCs HCFCs
Which of the following statements describe the advantages and disadvantages of the replacements for CFCs? Select all that apply.
HFCs are nontoxic and nonflammable. HFCs are considered greenhouse gases.
Which elements are found in HCFCs? Select all that apply.
Hydrogen Carbon Chlorine Fluorine
Which of the following radicals are responsible for ozone depletion? (Select all that apply.)
Hydroxyl Nitrogen monoxide
Which of the following correctly describes skin cancer?
It is caused by exposure to UVA and UVB radiation.
Resonance forms are correctly defined as _____.
Lewis structures for the same species that differ in the placement of electrons
Which of the following statements correctly describe a Lewis structure? Select all that apply.
Lone pairs are shown as pairs of dots on individual atoms. Bonding electrons are shown as lines or pairs of dots between two atoms.
Which of the following statements correctly describe a photon? Select all that apply.
Matter cannot absorb or emit a fraction of a photon. A photon is a particle of electromagnetic radiation.
Dinitrogen monoxide (N2O) breaks down to form the nitrogen monoxide (NO) radical, which results in ozone depletion. Which of the following is a natural source for N2O?
Microorganisms in soil and water
Does a sunscreen with an SPF of 100 block out twice as much harmful radiation as one with an SPF of 50? It is assumed that both sunscreens were applied in the same concentration on the skin.
No
What characterizes a free radical?
One or more unpaired electrons
UV-C radiation is absorbed by which two substances in the stratosphere?
Ozone Oxygen
Which of the following statements correctly describe the formation of ozone? Select all that apply.
Ozone is typically formed during a lightning storm. Ozone can be formed from O2.
Which of the following statements correctly describe polar stratospheric clouds (PSCs)? Select all that apply.
PSCs are composed of tiny ice crystals. PSCs provide a surface for chemical reactions to occur.
What type of clouds are composed of tiny icy crystals formed from a small amount of water vapor present in a specific region of the atmosphere?
Polar stratospheric clouds
Which of the following options correctly describe the unique conditions in the Antarctic that cause the region to have a disproportionately large hole in the ozone layer?
Polar stratospheric clouds formed in this region initiate reactions of benign species to more reactive species. Temperatures are as cold as -90°C. Winds in the area form a vortex that prevents warmer air from entering the Antarctic.
Which of the following statements correctly describe natural variations in stratospheric ozone levels? Select all that apply.
Random fluctuations in ozone concentrations occur. The amount of radiation emitted by the Sun varies over an 11- to 12-year cycle, which causes variations in ozone production.
Which color of visible light will have the lowest energy photons?
Red
Which of the following represents techniques that are currently used to quantify ozone levels in the atmosphere? (Select all that apply.)
Satellite-mounted detectors Weather balloons
Above which region of Earth is the largest ozone hole located?
South Pole
Draw the Lewis structure for the covalent molecule CCl4. Which of the following statements correctly describes the Lewis structure of CCl4? Select all that apply.
The Lewis structure of CCl4 contains four single bonds. The Lewis structure of CCl4 contains 12 lone pairs.
Which of the following options correctly describe the UV Index? Select all that apply.
The UV Index is based on the length of time required for skin damage to occur. A UV Index color-coded yellow indicates a moderate level of UV radiation.
Which of the following statements correctly characterize the ozone layer? Select all that apply.
The actual concentration of O3 in the ozone layer is fairly small. The ozone layer filters UV light from the Sun.
Why is ozone depletion greater over the South Pole than the Arctic?
The air above the North Pole is not as cold, so that fewer polar stratospheric clouds form.
Which of the following statements correctly describes the consequences of halting the production of CFCs?
There has been a slow decrease in the concentration of stratospheric chlorine since the halt in production of CFCs.
Energy is quantized. What does this mean?
There is a basic unit of energy that cannot be subdivided further.
Why do natural sources of chlorine not cause as much harm to the ozone layer as CFCs?
They are lost to rainfall before reaching the stratosphere
A wave of electromagnetic radiation has a wavelength of 450 nm. Which of the following options are correct for this radiation? Select all that apply. Assume that the speed of light is 3.00 × 10e8 m/s.
This wave has a frequency of 3.00×10e8 4.5×10e−7 3.00×10e8 4.5×10e-7 = 6.7 × 10e14 Hz. The wavelength is equal to 4.5 × 10e-7 m.
Mineral-based sunblock preparations may contain _______. (Select all that apply.)
TiO2 ZnO
Which of the following should be minimized for a suitable CFC replacement?
Toxicity
True or false: Sunscreens are transparent, whereas sunblocks are opaque.
True
Match each type of radiation correctly with either its source or its function.
UV radiation - This type of radiation is given off by the Sun and is harmful to humans. X-rays - This type of radiation is used in medical diagnosis and the determination of crystal structures. Gamma rays - This type of radiation is given off in nuclear decay. Microwaves - This type of radiation is used to cook food quickly.
Which of the following options correctly describe the different types of UV radiation? Select all that apply.
UV-C radiation has the shortest wavelength. UV-A is the least damaging to the Earth's surface. UV radiation with a wavelength of 300 nm is classified as UV-B radiation.
Match the type of radiant energy with the percentage of total energy emitted by the Sun.
Visible radiation - 39% IR radiation - 53% UV radiation - 8%
Which of the following regions of the electromagnetic spectrum have sufficient energy to break covalent bonds? (Select all that apply.)
X-ray Ultraviolet
Which of the following would correspond to types of radiation? (Select all that apply.)
X-rays from an X-ray machine at the hospital UV light from a black light Visible light from a candle
A nanometer is one _____ of a meter.
billionth
A substance that participates in a chemical reaction but is regenerated so that it undergoes no permanent change is called a(n) ______.
catalyst
Chlorofluorocarbons (CFCs) and their replacement compounds (HFCs and HCFCs) have a negative impact on our environment because they all ______.
contribute to global climate change
The bond formed between two nonmetals is called a(n) _____ bond. This bond involves the _____ of one or more electron pairs between the two atoms.
covalent; sharing
Replacing halogen atoms (such as Cl) in CFCs with hydrogen results in a(n) _____. Select all that apply.
decrease in boiling point decrease in molar mass
Energy and wavelength are related through the equation: E = h/wavelength . Match each symbol with the correct identity.
h - Planck's constant c - Speed of Light E - Energy per photon λ - Wavelength
Match each prefix or term to its correct meaning when applied to an organic compound.
hydro- C-H bonds are present fluoro- C-F bonds are present olefin C=C double bonds are present
Exposure to UV radiation causes the concentration of melanin in the skin to ______.
increase
Introducing too many H atoms into a potential replacement for CFCs causes a(n) _____ in flammability and a(n) _____ in boiling point.
increase; decrease
On average, the concentration of ozone _____ as one gets closer to either pole, with the exception being the seasonal ozone hole over the _____.
increases; Antarctic
Wavelength and frequency are _____ proportional to each other. As wavelength increases frequency will _____.
inversely; decrease
Exposure to UV radiation causes an increase in the concentration of the skin pigment known as
melanin
In general ozone (O3) is much _____ reactive than oxygen (O2).
more
The process by which green plants convert sunlight into stored chemical potential energy by producing glucose and oxygen is called ______.
photosynthesis
Although HFCs are a good replacement for CFCs in terms of their physical properties and effect on the ozone layer, these compounds _______.
play a role in global warming are greenhouse gases
An example of a __ state would be the concentration of ozone being replenished as fast as it is destroyed.
steady
UV-C radiation has the highest energy of all the types of radiation but it is not biologically damaging because it never reaches the Earth. UV-C radiation is instead absorbed in the _____ by oxygen and _____.
stratosphere; ozone
The region of the atmosphere closest to Earth is called the _____. The region of the atmosphere that contains the ozone layer is called the _____.
troposphere; stratosphere
The bonds in ozone (O3) are ______ than those in oxygen (O2). For this reason, UV radiation of ______ wavelength is sufficient to separate the atoms of ozone.
weaker; longer
Select the correct symbol and units for wavelength. More than one unit and/or symbol may be correct.
λ nm
Select the correct symbol for frequency.
ν