Chapter 02 - The Nature of Molecules and the Properties of Water Chapter 02 The Nature of Molecules and the Properties of Water Multiple Choice Questions Matter is composed of: A molecules B mass C energy D atoms Blooms Level: Remember Gradable: automatic LO: 02.01.01 Define an element based on its composition Section: 02.01 Topic: The Nature of Atoms All atoms possess the ability to work The term that is defined as the ability to work is: A matter B energy C molecules D space Blooms Level: Remember Gradable: automatic LO: 02.01.02 Describe how atomic structure produces chemical properties Section: 02.01 Topic: The Nature of Atoms 2-1 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water The number of protons in a given atom is equal to its: A neutron number B mass C atomic number D molecular number Blooms Level: Remember Gradable: automatic LO: 02.01.02 Describe how atomic structure produces chemical properties Section: 02.01 Topic: The Nature of Atoms Isotopes that are unstable and decay when their nucleus breaks up into elements with lower atomic numbers, emitting significant amounts of energy in the process, are called: A energetic B ionic C radioactive D isometric Blooms Level: Remember Gradable: automatic LO: 02.01.02 Describe how atomic structure produces chemical properties Section: 02.01 Topic: The Nature of Atoms Atoms containing a specific number of protons are called: A molecules B minerals C metals D elements Blooms Level: Remember Gradable: automatic LO: 02.02.01 Relate atomic structure to the periodic table of the elements Section: 02.02 Topic: Elements Found in Living Systems 2-2 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water Sugars dissolve well in water because of water's A polarity B ionic bonds C hydrophobic exclusion D cohesiveness Blooms Level: Understand Gradable: automatic LO: 02.03.03 Contrast polar and nonpolar covalent bonds Section: 02.03 Topic: The Nature of Chemical Bonds The negative logarithm of the hydrogen ion concentration in the solution is referred to as: A pH B atomic mass C -OH concentration D electronegativity E specific heat Blooms Level: Remember Gradable: automatic LO: 02.06.01 Define acids, bases, and the pH scale Section: 02.06 Topic: Acids and Bases Bicarbonate ions in the blood can absorb hydrogen ions, keeping pH balanced Bicarbonate is acting as a in blood A acid B alkaline C buffer D base Blooms Level: Understand Gradable: automatic LO: 02.06.01 Define acids, bases, and the pH scale Section: 02.06 Topic: Acids and Bases 2-3 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water Atomic nuclei contain protons and _ A moles B neutrons C isomers D ions Blooms Level: Remember Gradable: automatic LO: 02.01.01 Define an element based on its composition Section: 02.01 Topic: The Nature of Atoms 10 Carbon-12, Carbon-13 and Carbon-14 are examples of: A ions B isomers C molecules D isotopes Blooms Level: Remember Gradable: automatic LO: 02.01.02 Describe how atomic structure produces chemical properties Section: 02.01 Topic: The Nature of Atoms 11 Organisms are composed of molecules, which are collections of smaller units, termed: A monomers B atoms C electrons D polymers E ions Blooms Level: Remember Gradable: automatic LO: 02.01.01 Define an element based on its composition Section: 02.01 Topic: The Nature of Atoms 2-4 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water 12 Negatively charged subatomic particles that have almost no mass are called: A electrons B protons C neutrons D ions E polymers Blooms Level: Remember Gradable: automatic LO: 02.01.03 Explain where electrons are found in an atom Section: 02.01 Topic: The Nature of Atoms 13 Atoms of a single element that possess different numbers of neutrons are called: A isomers B polymers C ions D isotopes E monomers Blooms Level: Remember Gradable: automatic LO: 02.01.02 Describe how atomic structure produces chemical properties Section: 02.01 Topic: The Nature of Atoms 14 Cl + e-  Cl- is an example of a: A polymerization B ionization C reduction D oxidation Blooms Level: Understand Gradable: automatic LO: 02.01.03 Explain where electrons are found in an atom Section: 02.01 Topic: The Nature of Atoms 2-5 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water 15 When atoms gain or lose electrons, they become negatively or positively charged These negatively or positively charged atoms are known as A isotopes B ions C isomers D unstable atoms Blooms Level: Understand Gradable: automatic LO: 02.03.01 Predict which elements are likely to form ions Section: 02.03 Topic: The Nature of Chemical Bonds 16 When two atoms share a pair of electrons, the bonding is referred to as: A ionic B covalent C unstable D hydrogen Blooms Level: Remember Gradable: automatic LO: 02.03.02 Explain how molecules can be built from atoms joined by covalent bonds Section: 02.03 Topic: The Nature of Chemical Bonds 17 Water molecules are polar with ends that exhibit partial positive and negative charges These opposite charges allow water molecules to attract each other through: A ionic bonds B covalent bonds C hydrogen bonds D peptide bonds Blooms Level: Understand Gradable: automatic LO: 02.04.01 Relate how the structure of water leads to hydrogen bonds Section: 02.03 Topic: The Nature of Chemical Bonds 2-6 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water 18 An atom has 20 electrons and 20 neutrons What is the mass of this atom? A 10 B 20 C 40 D 80 Clarify Question  What is the key concept addressed by the question? The question asks about calculating the mass of an atom  What type of thinking is required? You are being asked to apply the definition of atomic mass to calculate an atomic mass  What key words does the question contain and what they mean? o Atomic mass is the sum of the masses of protons and neutrons in an atom We assume the mass of electrons is so small it doesn’t contribute to total mass Gather Content  What you know about atomic mass? How does it relate to the question? o The masses of a proton and of a neutron are both Consider Possibilities  What other information is related to the question? Which information is most useful? o There are 20 protons and 20 neutrons each with a mass of in this atom Choose Answer  Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer? o 20 protons + 20 neutrons = an atomic mass of 40 Reflect on Process  Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result? o This question asked you to apply the definition of atomic mass to calculate an atomic mass If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you confuse atomic number (the number of protons alone) with the atomic mass (the sum of protons and neutrons)? 2-7 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water Blooms Level: Apply Gradable: automatic LO: 02.02.01 Relate atomic structure to the periodic table of the elements Section: 02.02 Topic: Elements Found in Living Systems 2-8 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water 19 Sue was monitoring the oil spill into the Gulf of Mexico from an oil tanker From her observations, she noted that the oil was moving as large patches in the water It did not appear as though the oil was dissolving into the water Why did the oil not dissolve into the water? A Hydrophobic interactions B Surface tension C Sea water acts as a solvent D Water forms hydration shells E Water has a high heat of vaporization 2-9 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water Clarify Question  What is the key concept addressed by the question? The question asks why oil and water don’t mix  What type of thinking is required? You are being asked to apply your knowledge of the properties of water and oil to explain why the oil does not dissolve in water  What key words does the question contain and what they mean? o Dissolve – this means one compound mixes completely with a solvent like water Gather Content  What you know about water as a solvent? How does it relate to the question? o Water is a polar molecule, this means that other polar molecules or ions will dissolve in it These water loving molecules are called hydrophilic o Oil is a non-polar molecule and will dissolve better in a non-polar solvent These molecules are called hydrophobic, or water fearing Consider Possibilities  What other information is related to the question? Which information is most useful? o Water is a solvent with a high heat of vaporization and surface tension Water also forms surface tension However, none of these properties explain why oil does not dissolve in water Choose Answer  Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer? o The best answer is that oil is hydrophobic, meaning it does not interact well with water This is because water is a polar molecule and oil is non-polar Water has O-H bonds which not share electrons equally giving the O a partial negative charge and the H a partial positive charge In contrast oil is made up of C-H bonds and the electrons are shared more equally leading to no partial charges Because oil does not have these charges it is not attracted to the charges in water and does not dissolve well in water Reflect on Process  Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result? o This question asked you to apply the properties of water to explain why oil and water not mix well If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you know what the word hydrophobic meant? Did you have difficulty remembering which properties of water make it a good solvent for other polar molecules? 2-10 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water 69 Magnesium chloride is a salt formed with ionic bonds between one magnesium ion and two chloride ions Magnesium has two electrons in its outer shell and chlorine has seven electrons in its outer shell How are the electrons transferred between these atoms? A Chlorine is oxidized and magnesium is reduced B Both magnesium and chlorine are oxidized C Both magnesium and chlorine are reduced D Magnesium is oxidized and chlorine is reduced 2-81 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water Clarify Question  What is the key concept addressed by the question? The question asks about reduction and oxidations  What type of thinking is required? You are being asked to apply your knowledge to the formation of ions through reduction and oxidation  What key words does the question contain and what they mean? o Outer shell of electrons – an atom is most stable with a full outer shell of electrons It can obtain this by gaining or losing electrons Gather Content  What you know about oxidations and reductions? How does it relate to the question? o If an atom loses an electron it becomes oxidized and forms a positive charge o If an atom gains an electron it becomes reduced and forms a negative charge Consider Possibilities  What other information is related to the question? Which information is most useful? o Mg has extra electrons in its outer shell, so it will be most stable losing two electrons o Cl has electrons in its outer shell, so it will be most stable gaining one electron Choose Answer  Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer? o Mg will lose two electrons, forming Mg2+ and be oxidized in the process o Cl will gain one electron, forming Cl- and be reduced in the process Reflect on Process  Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result? o This question asked you to apply the structure of an atom to predict if it would become reduced or oxidized in forming an ion If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you realize that Mg would lose electrons and Cl would gain them? Did you remember that oxidations lose electrons and reductions gain electrons? 2-82 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water Blooms Level: Apply Gradable: automatic LO: 02.06.02 Relate changes in pH to changes in [H] Section: 02.06 Topic: Acids and Bases 70 The common basilisk lizard will run across water on its hind legs in an erect position when startled by predators This lizard has large feet and flaps of skin along its toes What properties of water allow this lizard to walk on water? A Hydrogen bonds absorb heat when they break and release heat when they form This helps to minimize temperature changes B The surface tension created by hydrogen bonds is greater than the weight of the lizard initially C Polar molecules are attracted to ions and polar compounds, making these compounds soluble D Hydrogen bonds hold water molecules together; many hydrogen bonds must be broken for water to evaporate Blooms Level: Understand Gradable: automatic LO: 02.05.02 Explain the relevance of waters unusual properties for living systems Section: 02.05 Topic: Properties of Water 71 How is the bond in F2 different from the bond in KCl? A F2 is covalent and KCl is ionic B F2 and KCl are both ionic C F2 is ionic and KCl is covalent Blooms Level: Understand Gradable: automatic LO: 02.03.02 Explain how molecules can be built from atoms joined by covalent bonds Section: 02.03 Topic: The Nature of Chemical Bonds 2-83 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water 72 Carbon has valence electrons and oxygen has Carbon dioxide would contain _ A four hydrogen bonds B two single covalent bonds C two double covalent bonds D one single covalent bond 2-84 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water Clarify Question  What is the key concept addressed by the question? The question asks about the formation of covalent bonds  What type of thinking is required? You are being asked to apply your knowledge of the structure of atoms to predict how many covalent bonds carbon dioxide could form  What key words does the question contain and what they mean? o Valence electrons – these are the electrons in the outer shell of an atom Gather Content  What you know about covalent bonds? How does it relate to the question? o Typically an atom is most stable if it has a full outer shell This can be accomplished by gaining, losing, or sharing electrons When two electrons are shared between two atoms this forms a covalent bond Consider Possibilities  What other information is related to the question? Which information is most useful? o The name carbon dioxide indicates that there are one carbon atom and two oxygen atoms in this molecule o Carbon has valence electrons, so it needs to share more electrons to get a full outer shell This means it can form covalent bonds o Oxygen has valence electrons, so it needs to share more electrons to get a full outer shell This means each oxygen atom can form covalent bonds Choose Answer  Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer? o The carbon atom can form a double bond with each of the oxygen atoms That will give the carbon atom bonds and each oxygen atom bonds needed to fill their outer shells The structure O=C=O would thus contain two double covalent bonds Reflect on Process  Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result? o This question asked you to apply the structure of an atom to predict how many bonds would form in carbon dioxide If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you have trouble figuring out how many bonds carbon and oxygen each needed to form to be stable? Were you confused on whether 2-85 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water all of the bonds were between C and O or did you try to make some O-O bonds? Blooms Level: Apply Gradable: automatic LO: 02.03.03 Contrast polar and nonpolar covalent bonds Section: 02.03 Topic: The Nature of Chemical Bonds 73 If water were non-polar it would not form hydrogen bonds At normal room temperatures this non-polar water would be _ A a gas B a liquid C a solid Blooms Level: Understand Gradable: automatic LO: 02.05.02 Explain the relevance of waters unusual properties for living systems Section: 02.05 Topic: Properties of Water 2-86 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water 74 Proteins are three dimensional molecules made of strands of amino acids (imagine a ball of string) There are 20 different amino acids used in proteins found in living organisms Some of these amino acids are polar and others are non-polar Where would a series of nonpolar amino acids most likely be located in a protein that is found in the cytosol of an animal cell? A On the surface of the protein B In the interior of the protein C At the very top of the protein D At the very bottom of the protein 2-87 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water Clarify Question  What is the key concept addressed by the question? The question asks about non-polar amino acids  What type of thinking is required? You are being asked to apply your knowledge of polarity to predict how this would affect the structure of a protein  What key words does the question contain and what they mean? o Polar – these are molecules in which electrons are not shared equally between atoms, leading to partial charges on the atoms o Non-polar – these are molecules in which electrons are shared equally between atoms, leading to no partial charges Gather Content  What you know about non-polar molecules? How does it relate to the question? o Non-polar molecules not interact well with water, which is a polar molecule These non-polar molecules actually interfere with the formation of hydrogen bonds between water molecules Consider Possibilities  What other information is related to the question? Which information is most useful? o The inside of an animal cell contains cytoplasm which is made up of a lot of water Thus the inside of the cell is a polar environment o Non-polar amino acids in the inside of a cell not interact well with the water and are repelled by the water Choose Answer  Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer? o The repulsion of non-polar amino acids by water will cause them to cluster in the center of the protein where they are shielded from water This is why most proteins are ball shaped, with the non-polar or hydrophobic amino acids in the center of the ball Reflect on Process  Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result? o This question asked you to apply polar and non-polar definitions to predict the structure of a protein If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you understand the difference between polar and non-polar 2-88 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water amino acids? Did you realize that the inside of the cell would be a polar environment? Did you know that non-polar groups will cluster near each other to be shielded from water? Blooms Level: Apply Gradable: automatic LO: 02.05.02 Explain the relevance of waters unusual properties for living systems Section: 02.05 Topic: Chemistry 2-89 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water 75 According to most car mechanics, plain water is the best coolant to use in an engine provided the engine is not being exposed to freezing temperatures If the car is subject to freezing temperatures then a mixture of water and ethylene glycol (antifreeze) is recommended but it does not cool as efficiently as plain water Why would ethylene glycol reduce the cooling efficiency of water? A Hydrogen bonds in water allow high levels of heat absorption and a large increase in temperature B Ethylene glycol raises the freezing point of water C Ethylene glycol has a lower heat capacity than water D Ethylene glycol has a higher heat capacity than water 2-90 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water Clarify Question  What is the key concept addressed by the question? The question asks about the ability of water to absorb heat  What type of thinking is required? You are being asked to apply your understanding of the properties of water to explain the effect of adding antifreeze  What key words does the question contain and what they mean? o Cooling efficiency – this is a measure of how well a solution can absorb heat Gather Content  What you know about the properties of water? How does it relate to the question? o Water has a very high heat capacity This means that it can absorb a lot of heat Consider Possibilities  What other information is related to the question? Which information is most useful? o Adding ethylene glycol decreases the cooling efficiency of the water in the radiator This is done to lower the freezing point of water, which keeps the radiator from freezing solid in the winter Choose Answer  Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer? o The ethylene glycol has a lower heat capacity than water, so adding ethylene glycol to the radiator decreases the amount of heat that the water can absorb Reflect on Process  Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result? o This question asked you to apply the properties of water to explain the ability of water to absorb heat If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you realize that the property of water relevant to cooling efficiency was its heat capacity? Did you recognize that the question was not asking about changes in the freezing point? 2-91 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water Blooms Level: Apply Gradable: automatic LO: 02.05.02 Explain the relevance of waters unusual properties for living systems Section: 02.05 Topic: Properties of Water 2-92 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water 76 Dennis had a history of heart disease in his family and was reducing his intake of saturated fats Saturated means each carbon atom is bonded to as many hydrogen atoms as it can accept If a carbon were bonded to two carbons, how many hydrogens could it accept? A B C D E 2-93 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water Clarify Question  What is the key concept addressed by the question? The question asks about forming covalent bonds  What type of thinking is required? You are being asked to apply your knowledge of the structure of an atom to predict how many bonds it can form  What key words does the question contain and what they mean? o Saturated fat – these fats have a backbone of C-C bonds with as many C-H bonds as possible Gather Content  What you know about covalent bonds? How does it relate to the question? o Carbon has valence electrons, and needs to share an additional electrons to have a full outer shell This means it needs to form covalent bonds Consider Possibilities  What other information is related to the question? Which information is most useful? o In a saturated fat there is a backbone of C atoms attached by covalent bonds giving a structure like: -C-C-Co These covalent bonds provide additional electrons, leaving a need for more for carbon to have a full outer shell Choose Answer  Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer? o To obtain the remaining electrons, each C atom forms covalent bonds with two H atoms Reflect on Process  Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result? o This question asked you to apply the structure of an atom to predict how many bonds would form in a saturated fat If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you understand what was meant by a saturated fat? Could you figure out how many total covalent bonds each C atom would form? 2-94 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education Chapter 02 - The Nature of Molecules and the Properties of Water Blooms Level: Apply Gradable: automatic LO: 02.03.02 Explain how molecules can be built from atoms joined by covalent bonds Section: 02.03 Topic: The Nature of Chemical Bonds 2-95 Copyright © 2017 McGraw-Hill Education All rights reserved No reproduction or distribution without the prior written consent of McGraw-Hill Education ... Water 22 The pH of your small intestines is around 7.5 and the pH of your large intestine can be 5.5 As substances travel from the small intestines to the large intestine, what would happen to... related to the question? Which information is most useful? o In moving from the small intestines to the large intestines the pH goes from 7.5 to 5.5, which means the substance is moving to a more