CHM1020 Exam 2
In the compound MgO, the Mg ion has a charge of _____, while the O ion has a charge of _____
+2, -2
What, approximately, is the highest concentration of CO2 measured in the Earth's atmosphere in modern times?
400ppm
A substance that participates in a chemical reaction but is regenerated so that it undergoes no permanent change is called a(n)
catalyst
Match each element with the appropriate charge in its ionic form. 1. Cl 2. Sr 3. S 4. Al
1. -1 2. +2 3. -2 4. +3
how many valence electrons do the following elements have? 1. C 2. Be 3. Ne 4. F
1. 4 2. 2 3. 8 4. 7
How many lone pairs would an oxygen atom have (a single O atom)?
2
A boron (B) atom has _____ valence electrons
3
Dobson unit is equivalent to ______ O3 molecules in a vertical column of air with cross-section of 1 cm2
3 × 10^16
What is meant by the term "carbon footprint" when applied to an individual?
An estimate of the amount of CO2 and other greenhouse gas emissions produced by the individual in a given time frame
cation
An ion with fewer electrons than its neutral atom is called a(n)
anion
An ion with more electrons than its neutral atom is called a(n)
Which color in the rainbow has the shortest wavelength?
Blue
Which human activity has the GREATEST net effect on atmospheric CO2 levels?
Burning fossil fuels
Which of the following human activities increase the levels of atmospheric CO2?
Burning fossil fuels Replacing trees with cultivated crops Respiration
The most significant step toward halting the depletion of the ozone layer was the call to stop the production of
CFCs
Which of the following options correctly describe variations in solar irradiance and its effect on Earth's climate?
Changes in the Earth's orbit can affect the amount of solar radiation that reaches the Earth. Seasonal variations in sunlight intensity affect local temperatures significantly.
CFCs always contain
Chlorine, carbon, and fluorine
The most electronegative element is
Fluorine
Which of these represents the best Lewis structure for acetylene (C2H2)?
H-C=-C-H
The most abundant greenhouse gas in Earth's atmosphere is
H2O water vapor
Which of the following statements correctly describe ions?
Ions are formed when atoms lose or gain electrons. F- is an example of an anion.
What is the effect of the absorption of infrared energy on matter?
It increases the vibration of chemical bonds
Which of the following has the greatest impact on global warming?
Levels of atmospheric greenhouse gases
Which atmospheric component does not contribute to global warming?
N2
Select the allotrope of oxygen whose bonds can be broken by UVB radiation
O3
Which of the following can be attributed to the atmosphere of planet Earth?
The Earth's average temperature is higher than expected when considering its distance from the Sun.
An ecological footprint estimates the biologically productive space required to support a particular lifestyle. Which of the following are included in this estimate? Select all that apply.
Sea surface Fresh water Land
What was the role of the IPCC (International Panel on Climate Change), established in 1988?
The IPCC was to assess both scientific and socioeconomic data relating to climate change.
How do mineral nanoparticles in sunscreens protect from UV radiation?
The particles absorb incoming UV light
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.
which of the following is true about CFCs
They are chemically persistent molecules, and are inert and nontoxic
frequency symbol
V
A single covalent bond is indicated by
a single solid line
The lewis structure for N2 has
a triple bond, two lone pairs
For an electron to jump from a lower level to a higher one, it must ________ energy
absorb
The proportion of incoming radiation that is reflected by a surface is called the ________. This quantity is a measure of the reflectivity of a surface.
albedo
ionic bond matches
attraction between oppositely charged ions
An estimate of the biologically productive space necessary to support a particular standard of living is called a(n)
ecological footprint
A highly reactive species with one or more unpaired electrons is called a(n)
free radical
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
Introducing too many Cl atoms into a potential replacement for CFCs causes a(n) _____ in flammability and a(n) _____ in boiling point.
increase, increase
In chemistry, the mole _______.
indicates amount of substance is abbreviated mol
In a(n) _____ compound electrons are transferred from one atom or group of atoms to another. Conversely, in a(n) _____ compound electrons are shared.
ionic, covalent
The speed of light in air
is independent of the wavelength and frequency of light.
As the wavelength of light decreases (gets shorter) what happens to the frequency of that light, assuming the speed of light stays the same?
it increases
The molar mass of any substance is the mass of 1 _______ of the particles of that substance
mol
During the Antarctic spring, ozone is destroyed at a greater rate than it is formed
on the surface of atmospheric ice crystals. in a process that is catalytic. in polar stratospheric clouds.
When only one pair of shared electrons is involved in a covalent bond, the linkage is called a __________ bond.
single
What shape would a molecule of carbon tetrachloride have?
tetrahedral
Calculate the wavelength of a wave with velocity of 5.1 x 104 m/s and frequency of 1.1 x 108 s-1.
4.6 x 10^ 4
steps for drawing a Lewis structure in the correct order, starting with the first step at the top of the list.
1. Count the number of outer electrons contributed by each atom 2. Add the valence electrons contributed by each individual atoms to determine the total number of outer electrons for the species 3. Arrange the outer electrons in pairs around the contributing atoms 4. Ensure that each atoms has a full outer shell
Rank the three types of UV radiation in order of increasing wavelength, starting with the shortest wavelength radiation at the top of the list.
UVC< UVB< UVA
When naming an ionic compound, the _____ is always named first. To name the anion, the root of the nonmetal name is added to the suffix _____.
cation; -ide
Which of the following statements correctly describe a photon?
matter cannot absorb or emit a fraction of a photon, a photon is a particle of electromagnetic radiation
mass ratio of H, mass percent of H
0.176, 17.6
mass ratio of N, mass percent of N
0.824, 82.4
Which of the following options correctly interpret the information provided by the balanced equation CH4 + 2O2 → CO2 + 2H2O?
1 molecule of CH4 reacts with 2 molecules of O2. 1 mole of CH4 produces 1 mole of CO2 when reacted with 2 moles of O2. 15 mol of CH4 will produce 15 mol of CO2 when burned completely in O2.
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. A CFC molecule is bombarded with UV light releasing a chlorine radical 2. Chlorine radicals react with ozone to produce ClO and Oxygen 3. ClOO decomposes to a chlorine radical and oxygen
Correctly order the steps required to determine the shape of a molecule, starting with the first step at the top of the list.
1. determine the number of outer electrons associated with each atoms in the molecule 2. arrange the outer electrons in pairs, ensuring that all atoms other than hydrogen obey the octet rule 3. determine the shape of the molecular by examining the position of the bonding and non bonding electron pairs with respect to each other
A mole of CO2 contains how many oxygen atoms?
1.20 x 10^24
Calculate the velocity of a wave with a frequency of 3.5 x 10-5 s-1 and wavelength of 5.1 x 108 m
1.8 x 10^4
To draw a Lewis structure, first add the number of outer (valence) electrons contributed by each atom to obtain the total number of outer electrons. What is this value for a molecule of C2H2?
10 outer electrons
Sunspots typically occur about every
11 years
What is the molar mass of dimethylglyoxime, C4H8N2O2?
116.12 g/mol
The history of average global temperature for the last 160,000 years is derived from isotopic analysis of ice layers in Antarctica. Scientists study the ________ ratio in ________.
1H/2H; H2O
In a vacuum all electromagnetic radiation travels at a constant speed:
3.00x10^8
WUKF FM transmits at 93.5 MHz. What is the wavelength of the electromagnetic radiation that carries the station's signal?
3.21 m
How much energy (in joules) would a photon of green light (wavelength 532 nm) have?
3.74 x 10^ -19
To draw a Lewis structure, first add the number of outer (valence) electrons contributed by each atom to obtain the total number of outer electrons. What is this value for a molecule of CF2Cl2?
32 total valence electrons
Calculate the mass of 2.50 × 104 molecules of nitrogen gas.
5.81 × 10^¯19 g
Give the number of outer (valence) electrons for an atom of bromine.
7
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
Which of the following statements correctly describe the general characteristics of a covalent 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, Electrons in a covalent bond are common property to both atoms that make up the bond
Which of the following greenhouse gases would require a wedge and dash representation in order to accurately depict its shape?
CCl2F2
During photosynthesis ________.
CO2 and H2O are consumed to produce stored glucose, sunlight is converted into stored chemical potential energy
Although carbon dioxide is the primary compound discussed with respect to global warming; of the common atmospheric components the global warming potential (GWP) of a carbon dioxide molecule is very low. Which statement best explains this pair of facts?
CO2 exists in relatively high concentrations
Which of the following elements will form a cation?
Ca and Rb (because they are both metals)
Which of the following ion combinations will result in an ionic compound that has a balanced number of positive and negative charges?
Ca2+ and 2 F -, 2 Li+ and S2-, Na+ and Br -
Which of the following formulas for ionic compounds are correct?
CaO Ca3N2
Which of the following radicals are responsible for ozone depletion by CFCs
ClO, Cl
Which statements describe an ionic compound?
Compounds that contain no molecules. Compounds formed when metals combine with nonmetals.
In the compound CrCl3 _______
Cr has a +3 charge Cl has a -1 charge
Replacing halogen atoms (such as Cl) in CFCs with hydrogen results in a(n) _
Decrease in boiling point and decrease in molar mass
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 describes the underlying principle used to determine molecular shape from a Lewis structure?
Each group of outer electrons around a central atom is located as far from the others as possible.
Which of the following options correctly describe how to draw a Lewis structure for a given molecule?
Each line between two atoms represents two electrons, The Lewis structure includes only the valence electrons for the molecule, The A-group number of a main-group element gives the number of valence electrons
True or false: Once the production of CFCs was halted there was a dramatic decrease in the amount of stratospheric chlorine.
False
Where is most of the carbon on earth stored?
In the form of fossil fuels and carbonate minerals and rocks
Which of the following statements correctly describe a Lewis structure?
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 options correctly describe each type of chemical compound?
Molecular compounds tend to contain nonmetals only, Nonmetals combine with metals to form ionic compounds.
Which of the following are three-dimensional representations of a molecule? Select all that apply.
Space-filling model Wedge-dash representation
Which of the following options correctly describe the UV Index?
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 options correctly describe albedo? Select all that apply.
The albedo of the Earth affects global temperatures. Albedo is the fraction of incoming radiation that is reflected by a surface. A more reflective surface will have a higher albedo than a less reflective one.
Which of the following conclusions were reached by the IPCC (International Panel on Climate Change)?
The average global temperature of the Earth is increasing. The burning of fossil fuels has a major impact on climate change. Human activities play an important role in climate change.
Which of the following options correctly describe how to name an ionic compound?
The cation is named first and the anion second, When naming the anionic portion of the ionic compound, the element name is changed to end in -ide.
Which of the following options correctly describe the greenhouse effect?
The greenhouse effect is a natural process. Atmospheric gases on Earth trap about 80% of the infrared radiation produced by the Earth, warming the planet. The greenhouse effect causes the average temperature on Earth to be higher than predicted when considering its distance from the Sun.
Select the options that correctly reflect the mass ratios and mass percentages of the elements in SO3.
The mass ratio of S is 0.400. The mass percentage of O is 60.0%.
Which statement correctly describes the procedure used to predict the ion formed by Group 1 and Group 2 elements (part of the main groups elements) ?
The metal loses enough electrons to attain the same number as its nearest noble gas.
Which of the following statements correctly describe molar mass?
The molar mass of oxygen is 16.00 g/mol. This means that 1 mole of oxygen atoms has a mass of 16.00 g. The periodic table can be used to calculate the molar mass of any substance. The molar mass of a molecular substance is the mass per mole of its molecules.
Which of the following statements correctly describe the mole?
The number of particles in a mole is called Avogadro's number. One mole of any substance contains 6.02 x 10^23 particles.
Which conclusion was considered "very likely" in the 2014 report of the Intergovernmental Panel on Climate Change?
The observed warming of the past 100 years is due solely to climate variability
Which of the following options correctly describe the steps required to determine the shape of a molecule? Select all that apply.
The shape of the molecule is dictated by the most stable arrangement of the outer electron pairs. The Lewis structure of the molecule must be drawn first. Both bonding and nonbonding electron pairs must be considered.
Which of the following options correctly differentiate between weather and climate? Select all that apply.
The term "climate" refers to regional trends in temperatures, rainfall, etc. Weather includes daily variations in temperature and rainfall at a single location. The term "weather" refers to events that have a relatively short duration.
H2O2 (connectivity is HOOH)
This molecule possesses no multiple bonds
HCN
This molecule possesses one triple bond
CS2
This molecule possesses two double bonds
Which of the following is a common ingredient in mineral-based sunblock formulations?
TiO2 or ZnO
T/F: CFCs are inert, nontoxic compounds
True
Which of the following options correctly describe the different types of UV radiation? Select all that apply.
UV radiation with a wavelength of 300 nm is classified as UV-B radiation, UV-A is the least damaging to the Earth's surface, UV-C radiation has the shortest wavelength
Which of the following regions of the electromagnetic spectrum have sufficient energy to break covalent bonds?
UV, X-ray
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
covalent bond
attraction between two nuclei and a shared pair of electrons
Both Venus and Earth have higher average surface temperatures than expected because _____.
both planets have atmospheres that trap radiation
Which atom in a molecule of CH3Cl would contain the partial negative charge? (this relates to electronegativity)
chlorine
Any bond that involves the sharing of two electrons is known as a(n) ________ bond.
covalent
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
Lewis structures are used to represent covalent compounds. Shared electron pairs are shown either as pairs of ________ or lines and only _______ electrons are shown
dots, valence or outer
In the formation of ionic compounds a nonmetal will ______ electrons to form an ion with the same number of electrons as the nearest ______ gas.
gain; noble
Greenhouse gases have a _____ effect on global warming than other anthropogenic forcings
greater
Wavelength and frequency are _____ proportional to each other. As wavelength increases frequency will _____.
inversely, decrease
In the formation of ionic compounds a metal will ______ electrons and a nonmetal will ______ electrons to form an ion with the same number of electrons as the nearest ______ gas.
lose; gain; noble
one _________ of any substance contain Avogardo's number of particles
mol
Chemists use the _____ as a unit of amount of substance.
mole
In general ozone (O3) is much _____ reactive than oxygen (O2)
more
The charge of an ion with more electrons than its neutral atom is
negative
Consider the balanced equation 2H2 + O2 → 2H2O. The coefficients (numbers in front of the formulas) correspond to the number of particles of each substance involved in the reaction, which is proportional to the _____ of each substance
number of moles
The chemistry of carbon-based compounds is called ______ chemistry.
organic
frequency is usually measured as the distance between two _________ or two troughs
peaks/ crests
Which of the following can cause electrons in a ground state to go to a higher level excited state?
photon absorption
Electromagnetic radiation consists of particles called ______________, each of which has a discrete amount, or quantum, or energy, However, since electromagnetic radiation also has wave properties, each particle is also characterized by a specific ____________ and frequency
photons, wavelengths/ energy
The process by which green plants convert sunlight into stored chemical potential energy by producing glucose and oxygen is called
photosynthesis
The charge of an ion with fewer electrons than its neutral atom is
positive
structural formula
representation of how atoms are arragned, omitting lone pairs of electrons
Lewis structure
representation of how atoms are connected, including lone pairs of electrons
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
shared/bonding, lone
Chemical formula
shows only types and ratios of atoms present
Draw the Lewis structure for the covalent molecule CCl4. Which of the following statements correctly describes the Lewis structure of CCl4?
the Lewis structure of CCl4 contains 12 lone pairs, the Lewis structure of CCl4 contains four single bonds
frequency
the number if wave cycles per second
Organic chemistry is __
the study and production of carbon-containing compounds
Lewis structure for N2
triple bond, two lone pairs
Which of the following is the correct Lewis structure for the molecule OF2?
two bonds, 8 lone pairs
DNA, the genetic material of living organisms, is damaged by light in the
ultraviolet region, especially below a wavelength of 320 nm.
Electronegativity generally increases _______ on the periodic table, excluding noble gases.
up and to the right
Electrons that are found in the highest energy level are called
valence electrons
The most stable molecular arrangement is the one in which the ___________electron groups are as far apart as possible, to minimize electron-electron___________
valence, interaction
When a molecule absorbs an infrared photon it contributes to the ________energy of that molecule.
vibrational
wavelenght formula
wave velocity/ frequency
the distance a wave treavels during one cycle
wavelength
equation for velocity (speed) of a wave
wavelength x frequency
wavelength symbol
λ or nm
