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introductory chemistry atoms first
Introductory Chemistry Atoms First 5th Edition Steve Russo And Michael Silver - Solutions
Hydrogen bonding is (a) The name given to the chemical bond in the H—H or H2 molecule.(b) A particularly strong type of dipolar interaction.(c) As strong as a chemical bond.(d) When hydrogen bonds to any other element.
In Practice Problem 7.7, you should have predicted that, based solely on London forces, PH3 (18 electrons) has a higher boiling point than NH3 (10 electrons). In fact, this is not the case. Explain why.Data from Problem 7.7Draw a dot diagram for NH3 and one for PH3.Is either molecule polar? (The
A hydrogen bond between molecules can occur (a) Only if the molecules involved are nonpolar.(b) Only if the molecules possess a hydrogen atom bound to O, N, or F.(c) Only if full charges develop on the atoms instead of partial charges.(d) Only in the absence of dispersion forces.
Draw some molecules of ammonia, NH3, and use dotted lines to show the hydrogen bonding between them.
A network solid is (a) The easiest of solids to melt.(b) Made up of ions bound to one another via ionic bonds.(c) Made up of molecules attracted to one another.(d) Made up of atoms covalently bound to one another.
For the hydrogen halides, the order of boiling points is HF > HI > HBr > HCl.(a) Why does HF have the highest boiling point?(b) Why is the boiling point of HI greater than that of HBr and HCl?
Sodium oxide, Na2O, is a white-gray powder that sublimes (goes directly from solid to gas) at 1275 °C. Is sodium oxide a molecular or nonmolecular solid?
How is a piece of iron similar to a piece of sodium chloride in terms of the forces that must be overcome to melt it?
Elemental sulfur is a yellow solid that melts at 113 °C. Studies show sulfur to be a molecular solid consisting of S8 molecules held together in a lattice. What forces must be overcome to melt the solid?
The following are solids at room temperature (about 25 °C). Classify them as molecular, ionic, network, or metallic:(a) Zirconium, Zr, mp = 1852 °C(b) Lead, Pb, mp = 328 °C(c) Calcium nitride, Ca3N2, mp = 1195°C(d) Graphite form of carbon, C, sublimes at 3652°C(e) Yellow phosphorus, P4, mp =
Describe as completely as you can how small molecules like N2 and O2 behave at the molecular level in a warm room.
Consider cooling a gas so that it gets colder and colder.(a) Explain why this would eventually cause the gas to condense into a liquid.(b) Explain what would happen to this gas if you could somehow turn off all intermolecular forces.
What does the kinetic energy of molecules have to do with changing phases?
Is it incorrect to say that molecules are motionless in the liquid phase? Explain.
Explain in molecular terms how heating causes a liquid to change to the gas phase.
Water vapor liquefies when cooled below 100 °C. Gaseous nitrogen liquefies when cooled below –196 °C. What does this information tell you about the relative strengths of the intermolecular forces for these molecules?
Why are liquids and solids referred to as condensed phases?
Why does a gas expand to fill the container it is in, but a liquid and a solid do not?
On the molecular level, describe each phase of matter with respect to the amount of order present.
For this question, you should consider only polarity. Molecule A—B has a smaller dipole moment than molecule C—D.(a) Which molecule has the higher freezing point? Explain why.(b) Which molecule has the higher boiling point? Explain why
Draw a picture that shows how three polar HBr molecules in the gas phase would attract one another. What kind of intermolecular force is involved?
Explain what gives rise to London forces and when they occur.
Would you expect CCl4 or CBr4 to have the higher boiling point? Explain your answer.
Chloromethane (CH3Cl) has a much higher boiling point than methane (CH4). Give two reasons for this.
Propane (C3H8) is a gas at room temperature, whereas octane (C8H18) is a liquid. Explain why this is so.
What is wrong with the statement “London forces are always weaker than dipole–dipole forces”?
When discussing the intermolecular forces between methanol molecules, chemists usually ignore any London forces between them. Why are they justified in doing this? H HC-O. H H Methanol
Consider the molecules HF and HCl. The electronegativities of the atoms involved are H, 2.1; Cl, 3.0; F, 4.0.(a) Which of the two molecules is more polar? Explain your answer.(b) For which substance are the dipole–dipole attractions between the molecules stronger? Explain your answer.(c) Which
Predict which compound in each pair will have the higher melting point, and explain why for each pair.(a) CS2 or CCl4(b) Cl2 or F2(c) CH4 or NH3(d) CH3Cl or Cl4
Long-chain hydrocarbon molecules of the type CH3(CH2)20CH3 are solids and are used for things like waxes. The CH bonds are essentially nonpolar. Why are waxes solid at room temperature?
Which of the molecules below would not form hydrogen bonds?(a) CH3OH(b) CH3OCH3(c) CH3COOH(d) NH3(e) None of these would form hydrogen bonds.
What is so special about hydrogen atoms that makes hydrogen bonding possible?
Consider molecules of the type H2A, where A is a group VIA atom (O, S, Se, Te). Their relative boiling points are shown below.(a) Why is the boiling point trend H2S 2Se 2Te?(b) The boiling point of H2O is well above the line that the others are on. Explain why this is so. Boiling point H₂O H₂S
Two different compounds have the same elemental composition, C3H8O. One has a low boiling point and the other a much higher boiling point. What attractive force must be present in one of these compounds that is not present in the other?
What do we mean by induced dipole when discussing London forces?
Examine the diagram of DNA on page 265 to answer this question: Why can hydrogen bonds form in DNA? DNA molecule Derm Strand- Four kinds. of "teeth" Stretch of DNA "unzipped" for reading Record of information - from DNA, used to make proteins NU Hydrogen bonds Molecular "read head" -reading
Why do we use dotted lines rather than solid lines to represent hydrogen bonds?
Why would either covalent bonds or London forces be inappropriate for attaching the two strands of DNA to each other?
How is it possible for a nonpolar molecule to have a higher boiling point than a polar one?
What is the fundamental difference between a molecular substance and a nonmolecular substance?
Is it sometimes, always, or never possible to tell from a compound’s formula whether it is a molecular or nonmolecular substance?
What do we mean by a “lattice of ions”?
In general, nonmolecular solids have much higher melting points than molecular solids. Why is this so?
What is a network covalent substance? Give an example.
What evidence is there that metallic bonds can be as strong as ionic or covalent bonds?
Predict which compound in each pair will have the higher melting point, and explain why for each pair.(a) HI or KI(b) Na2O or H2O(c) CaF2 or HF(d) SiO2 or CO2
All of the following are solids at room temperature. Classify them as molecular, ionic, network, or metallic.(a) Potassium (K), mp = 64 °C(b) Potassium chloride (KCl), mp = 770°C(c) Red phosphorus (P), mp = 590°C(d) Boron triiodide (BI3), mp = 50°C
How does the attraction between two molecules depend on the distance between them?
Why should the attraction between two water molecules depend on how they are oriented with respect to each other? Use drawings to illustrate your answer.
Describe how the molecules in a liquid behave as the temperature of the liquid increases.
Solid ice is less dense than liquid water. What does this say about how many water molecules there are per unit volume of ice relative to how many water molecules there are per unit volume of liquid water?
Which of the following best describes a liquid:(a) The phase of matter in which particles are typically separated by the least distance.(b) The phase of matter in which particles are in a fixed, rigid arrangement(c) The phase of matter in which particles completely fill the volume of their
At 25°C, fluorine, F2, and chlorine, Cl2, are gases but bromine, Br2, is a liquid. What does this say about the intermolecular forces in bromine relative to those in fluorine and chlorine?
In which of the following are there no dipole–dipole forces between molecules? Justify your answer.(a) AsH3(b) CO2(c) H2O(d) SeCl2
Which is more likely to be a gas at room temperature, CH4 or CH2Cl2? Justify your answer.
Which of the following does not form hydrogen bonds? Justify your choice.(a) Methyl alcohol, CH3OH(b) Hydrofluoric acid, HF(c) Ammonia, NH3(d) Methane, CH4
Which of the following would you expect to have the highest boiling point? Justify your choice.(a) Propane, C3H8(b) Carbon dioxide, CO2(c) Ethyl alcohol, CH3CH2OH(d) Methyl fluoride, CH3F
Which of the following would most likely be a gas at room temperature? Justify your choice.(a) NaCl(b) C2H2(c) Na metal(d) CH3F
(a) Name the strongest intermolecular force in CH3OH, CH3Cl, CH3CH3, and CH3CH2CH3.(b) Rank these molecules from lowest to highest boiling point.
Acetic acid,is very soluble in water because of the many hydrogen bonds that can form. Add water molecules to this drawing and show the hydrogen bonds possible. H₂C :O: С Н
(a) Rank these molecules in order of increasing boiling point:(b) State your reason for the order you chose in part (a). Br Br-C-Br Br Br Br H H-C-H H CI-CI
Show how two CH2Cl2 molecules in the liquid phase are oriented with respect to each other and explain why the molecules align this way.
(a) Rank these molecules in order of increasing boiling point:(b) State your reason for the order you chose in part (a). H H-C-OH H H-H H H-C-H H H-Cl
Which compounds would you expect to experience only London forces? Explain your choices.(a) Carbon tetrabromide, CBr4(b) Methyl bromide, CH3Br(c) Phosphorous tribromide, PBr3(d) Boron tribromide, BBr3
Name the strongest intermolecular force expected in(a) Boron trifluoride, BF3(b) 1-Propanol, CH3CH2CH2OH(c) Xenon, Xe(d) Hydrogen fluoride, HF(e) Hydrogen iodide, HI
Which of the following do you expect to be nonmolecular solids?(a) Sodium hydroxide, NaOH(b) Solid ethanol, CH3CH2OH(c) Iron, Fe(d) Solid silane, SiH4
SiO2, the main component of glass, is a solid at room temperature, and CO2 is a gas at room temperature. How do the structures of these compounds explain this fact?
Arrange these substances in order of increasing melting point: CH3OH, SiO2, C2H6, NaCl.
Ethylene glycol, CH2OHCH2OH, and pentane, C5H12, have approximately the same molar mass. Nevertheless, one of these compounds boils at 198°C, and the other boils at 36°C. Which compound boils at which temperature? Use an argument based on intermolecular forces to justify your choice.
Both diamond and graphite are network solids consist solely of carbon atoms:In diamond, every carbon atom is bonded to four other carbon atoms. In graphite, every carbon atom is bonded to three other carbon atoms, creating sheets of atoms that lie on top of one another.(a) Which type of
Sketch the hydrogen bonds present in the liquid 1-propanol, CH3CH2CH2OH.
When considering which is stronger, a covalent bond or an ionic bond, why is it fairer to contrast the melting points of diamond and NaCl than to contrast the melting points of ice and NaCl?
Metallic bonding is often described as a lattice of metal cations in a sea of valence electrons. What is it about metallic bonding that allows it to be described in this fashion?
As you go down the column of noble gases in the periodic table, the boiling point increases. Explain this trend.
Eicosane, C20H42, has a higher melting point and a higher boiling point than water, even though water has hydrogen bonds between molecules and eicosane does not. Explain how this can be.
Most covalent molecular substances have much lower melting points than ionic substances. What does this say about the strength of a covalent bond relative to the strength of an ionic bond? Explain your answer.
Consider the compounds titanium tetrachloride (TiCl4) and zirconium tetrachloride (ZrCl4). Zirconium is in the same group as titanium on the periodic table, and both Ti–Cl and Zr–Cl polar covalent bonds are quite strong. TiCl4 has a melting point of –25°C (i.e., it is a liquid at room
Arrange in order of increasing boiling point:CO2, SO2, CH3CH2OH, Al.
The three molecules below increase steadily in molar mass from left to right. However, their boiling points do not. Explain why the boiling points do not also steadily increase from left to right. H H H Molar mass 17.0 g/mol Boiling point -33.3 °C F :2 F F 71.0 g/mol -85.1 °C CI CI CI 120.4
What is wrong with the following diagram when it comes to explaining London forces?
Consider the two square-planar molecules shown below. Which would you expect to have a higher boiling point, and why? F CI-Xe Cl 1-8 F (a) Cl F-Xe-Cl T F (b)
CO2 is a linear molecule, but just suppose it was possible to do the following (see below). If you could, what would you predict would happen to its melting point? Explain. 0=C=0 0-
For each part of this question, choose two different species from the list below, and illustrate the indicated intermolecular interaction with a dotted line. Be sure you show all charges involved in each interaction. (Use +, -, δ+, δ-, δδ+, and δδ- where appropriate.)If it is not possible to
For each part of this problem, redraw both of the molecules, orienting them in a way that allows you to clearly show (using a dotted line) a hydrogen bond between them. If it is not possible to form a hydrogen bond between the two molecules, then write NA (not applicable).
Rank the molecules below in order of increasing boiling point. Cl [T H—C—H H-C-F 1 -F2 F NH₂ H-CH H H 3 P H 4 H I-Br 5
Some bacteria have evolved in such a way to render the antibiotic Vancomycin ineffective. How did they accomplish this (make sure to explain the role of intermolecular forces)?
Predict the formula of the compound that forms between carbon and chlorine.
Suppose, instead of NaCl, we considered the ionic compound magnesium oxide, MgO, made from Mg2+ cations and O2– anions. Judging just from the charges, would the force of attraction between the ions in MgO be greater or smaller than in NaCl? By how much?
Regarding an ionic bond:(a) It forms due to transfer of one or more electrons from one atom to another.(b) It is the name given to the attractive force between oppositely charged ions that are in contact.(c) It is what holds an ionic lattice together.(d) All of the above.
Predict the formula of the compound that forms between phosphorus (P) and hydrogen.
Would you expect these two molecules to have nearly identical properties? Η Η Ο Ἡ H Η2Ο, H
Work together to finish the following statement:“You don’t need Greek numerical prefixes when naming simple ionic compounds because . . . ”
NaCl is not considered to be a molecular substance because:(a) It is an ionic compound with no discrete molecules in its solid lattice.(b) It is a molecular substance. That’s why we can write its formula.(c) It is made from more than one element.(d) Only one of the elements is an ion in the
Predict the formula of the compound that forms between silicon (Si) and bromine (Br).
How many valence electrons does each atom in the methane molecule have? Double-count shared electrons. HTCIH Η H-C-H Η
A covalent bond:(a) Is the name given to the attractive force between atoms in a molecule.(b) Is strong because the electrons in the bond can be attracted to two nuclei instead of just one.(c) Is formed only by the sharing of valence electrons.(d) All of the above.
In forming molecules, atoms can share unpaired electrons in order to achieve an octet in their valence shell. Hydrogen is an exception. What number of electrons does hydrogen “want,” and why is this number not eight?
How many valence electrons does a carbon atom normally have? How many valence electrons does it have in the methane molecule? How many electrons did it gain, and how many covalent bonds to hydrogen did it form?
When two electrons are shared between atoms in a covalent bond, we say:(a) Each atom owns one of the shared electrons.(b) Each atom owns both of the shared electrons.(c) Neither atom owns the shared electrons.(d) One atom owns both electrons and the other owns none of the electrons.
What is the molecular formula of the compound that forms between H atoms and F atoms? Justify your answer with dot diagrams.
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