Concept explainers
Draw electron-dot structures for the following molecules, indicating any unshared electron pairs. Which of the compounds are likely to act as Lewis acids and which as Lewis bases?
(a) AlBr3
(b) CH3CH2NH2
(c) BH3
(d) HF
(e) CH3SCH3
(f) TiCl4
a) AlBr3
Interpretation:
Electron dot structure for AlBr3 indicating any unshared electron pairs is to be drawn. Whether it will act as Lewis acid or Lewis base is also to be stated.
Concept introduction:
A covalent bond formed by sharing of two electrons between two atoms in a molecule is usually indicated by electron-dot structures in which valence electrons are represented as dots. Thus aluminum has three dots to represent its 3s23p1electrons, bromine has seven dots to represent its 4s24p5 electrons. A stable molecule results whenever all the atoms except hydrogen in a molecule achieve in their valence shell eight dots and hydrogen achieve two dots. The electrons present in the inner shells of the atoms are not shown.
Lewis acids are electron pair acceptors while Lewis bases are electron pair donors.
To give:
The electron dot structure for AlBr3 indicating any unshared electron pairs and to state whether it will act as Lewis acid or Lewis base.
Answer to Problem 42AP
The electron–dot structure for AlBr3 indicating any unshared electron pairs can be given as
It will act as a Lewis acid.
Explanation of Solution
Aluminum atom has three electrons (3s23p1) in its valence shell. It has used all the three electrons in forming three Al- Br bonds. So it has no lone pair of electrons. The bromine atom has seven electrons in its valence shell (4s24p5). Out of these seven electrons, each bromine has used one electron for forming Al-Br bond and thus has the remaining six electrons as three lone pairs. AlBr3 will act as Lewis acid since the central aluminum atom requires two more electrons to complete its octet.
The electron–dot structure for AlBr3 indicating any unshared electron pairs can be given as
It will act as a Lewis acid.
b) CH3CH2NH2
Interpretation:
Electron dot structure for CH3CH2NH2 indicating any unshared electron pairs is to be drawn. Whether it will act as Lewis acid or Lewis base is also to be stated.
Concept introduction:
A covalent bond formed by sharing of two electrons between two atoms in a molecule is usually indicated by electron-dot structures in which valence electrons are represented as dots. Thus hydrogen has one dot to represent its 1s1 electron, carbon has four dots to represent its 2s22p2 electrons, and nitrogen has five dots to represent its 2s22p3 electrons. A stable molecule results whenever all the atoms except hydrogen in a molecule achieve in their valence shell eight dots and hydrogen achieve two dots. The electrons present in the inner shells of the atoms are not shown.
Lewis acids are electron pair acceptors while Lewis bases are electron pair donors.
To give:
The electron dot structure for CH3CH2NH2 indicating any unshared electron pairs and to state whether it will act as Lewis acid or Lewis base.
Answer to Problem 42AP
The electron–dot structure for CH3CH2NH2 indicating any unshared electron pairs can be given as,
It will act as a Lewis base.
Explanation of Solution
Carbon atom has four electrons (2s22p2) in its valence shell. Both carbons have used all the four electrons in forming four bonds with other atoms. So they do not possess any lone pair of electrons. The nitrogen atom has five electrons in its valence shell (2s22p3). Out of these five electrons, nitrogen has used three electrons for forming one C-N and two N-H bonds and thus has the remaining two electrons as a lone pair. CH3CH2NH2 will act as Lewis base since the nitrogen atom can donate a pair of electrons to other species.
The electron–dot structure for CH3CH2NH2 indicating any unshared electron pairs can be given as,
It will act as a Lewis base.
c) BH3
Interpretation:
Electron dot structure for BH3 indicating any unshared electron pairs is to be drawn. Whether it will act as Lewis acid or Lewis base is also to be stated.
Concept introduction:
A covalent bond formed by sharing of two electrons between two atoms in a molecule is usually indicated by electron-dot structures in which valence electrons are represented as dots. Thus boron has three dots to represent its 2s22p1electrons, hydrogen has one dot to represent its 1s1 electron. A stable molecule results whenever all the atoms except hydrogen in a molecule achieve in their valence shell eight dots and hydrogen achieve two dots. The electrons present in the inner shells of the atoms are not shown.
Lewis acids are electron pair acceptors while Lewis bases are electron pair donors.
To give:
The electron dot structure for BH3 indicating any unshared electron pairs and to state whether it will act as Lewis acid or Lewis base.
Answer to Problem 42AP
The electron–dot structure for BH3 indicating any unshared electron pairs can be given as,
It will act as a Lewis acid.
Explanation of Solution
Boron atom has three electrons (2s22p1) in its valence shell. It has used all the three electrons in forming three B- H bonds. So it has no lone pair of electrons. Each hydrogen atom has one electron in its valence shell (1s1) which they utilize in forming the B-H bonds. BH3 will act as Lewis acid since the central boron atom requires two more electrons to complete its octet.
The electron–dot structure for BH3 indicating any unshared electron pairs can be given as,
It will act as a Lewis acid.
d) HF
Interpretation:
Electron dot structure for HF indicating any unshared electron pairs is to be drawn. Whether it will act as Lewis acid or Lewis base is also to be stated.
Concept introduction:
A covalent bond formed by sharing of two electrons between two atoms in a molecule is usually indicated by electron-dot structures in which valence electrons are represented as dots. Thus fluorine has seven dots to represent its 2s22p5 electrons, hydrogen has one dot to represent its 1s1 electron. A stable molecule results whenever all the atoms except hydrogen in a molecule achieve in their valence shell eight dots and hydrogen achieve two dots. The electrons present in the inner shells of the atoms are not shown.
Lewis acids are electron pair acceptors while Lewis bases are electron pair donors. To give: The electron dot structure for HF indicating any unshared electron pairs and to state whether it will act as Lewis acid or Lewis base.
Answer to Problem 42AP
The electron–dot structure for HF indicating any unshared electron pairs can be given as
It will act as a Lewis acid.
Explanation of Solution
Fluorine atom is the most electronegative element and hence the H-F bond is highly polarized. The electrons in the bond are more concentrated on F rather than on H. The hydrogen is thus electron deficient and it can accept a pair of electrons from a Lewis base. Hence HF is likely to behave as Lewis acid.
The electron–dot structure for HF indicating any unshared electron pairs can be given as
It will act as a Lewis acid.
e) CH3SCH3
Interpretation:
Electron dot structure for CH3SCH3 indicating any unshared electron pairs is to be drawn. Whether it will act as Lewis acid or Lewis base is also to be stated.
Concept introduction:
A covalent bond formed by sharing of two electrons between two atoms in a molecule is usually indicated by electron-dot structures in which valence electrons are represented as dots. Thus hydrogen has one dot to represent its 1s1 electron, carbon has four dots to represent its 2s22p2 electrons and sulfur has six dots to represent its 3s23p4 electrons. A stable molecule results whenever all the atoms except hydrogen in a molecule achieve in their valence shell eight dots and hydrogen achieve two dots. The electrons present in the inner shells of the atoms are not shown.
Lewis acids are electron pair acceptors while Lewis bases are electron pair donors.
To give:
The electron dot structure for CH3SCH3 indicating any unshared electron pairs and to state whether it will act as Lewis acid or Lewis base.
Answer to Problem 42AP
The electron–dot structure for CH3SCH3 indicating any unshared electron pairs can be given as,
It will act as a Lewis base.
Explanation of Solution
Carbon atom has four electrons (2s22p2) in its valence shell. Both carbons have used all the four electrons in forming four bonds with other atoms. So they do not possess any lone pair of electrons. The sulfur atom has six electrons in its valence shell (3s23p4). Out of these six electrons, sulfur has used two electrons for forming two C-S bonds and thus has the remaining four electrons as two lone pairs. CH3SCH3 will act as Lewis base since the sulfur atom can donate a pair of electrons to other species.
The electron–dot structure for CH3SCH3 indicating any unshared electron pairs can be given as,
It will act as a Lewis base.
f) TiCl4
Interpretation:
Electron dot structure for TiCl4 indicating any unshared electron pairs is to be drawn. Whether it will act as Lewis acid or Lewis base is also to be stated.
Concept introduction:
A covalent bond formed by sharing of two electrons between two atoms in a molecule is usually indicated by electron-dot structures in which valence electrons are represented as dots. A stable molecule results whenever all the atoms except hydrogen in a molecule achieve in their valence shell eight dots and hydrogen achieve two dots. The electrons present in the inner shells of the atoms are not shown.
Lewis acids are electron pair acceptors while Lewis bases are electron pair donors.
To give:
The electron dot structure for TiCl4 indicating any unshared electron pairs and to state whether it will act as Lewis acid or Lewis base.
Answer to Problem 42AP
The electron–dot structure for TiCl4 indicating any unshared electron pairs can be given as,
It will act as a Lewis acid.
Explanation of Solution
The chlorine atom has seven electrons in its valence shell (3s23p5). Out of these seven electrons, each chlorine has used one electron for forming Ti-Cl bond and thus have the remaining six electrons as three lone pairs. Titanium is a transition element. Transition elements utilize the d orbitals in the penultimate shell also along with orbitals of the valence shell during bonding. It has the configuration 3d24s2. It has used all the four electrons in forming four Ti-Cl bonds.
The d orbitals can have a maximum of ten electrons. In TiCl4, the titanium atom has empty d orbitals to accommodate electrons donated by a Lewis base. Hence TiCl4 will act as Lewis acid.
The electron–dot structure for TiCl4 indicating any unshared electron pairs can be given as,
It will act as a Lewis acid.
Want to see more full solutions like this?
Chapter 2 Solutions
Organic Chemistry
- Write the Lewis structures of the reactants and product of each of the following equations, and identify the Lewis acid and the Lewis base in each: (a) CS2+SHHCS3 (b) BF3+FBF4 (c) I+SnI2SnI3 (d) Al(OH)3+OHAl(OH)4 (e) F+SO3SFO3arrow_forward1. Which of the following can act as a Lewis acid? (Hint : In each case, draw the Lewis electron dot structure of the molecule or ion. Are there lone pairs of electrons on the central atom? If so, it can be a Lewis base. Does the central atom lack an electron pair? If so, it can behave as a Lewis acid.) PH3 BCl3 H2S HS−arrow_forwardHydrazine, N2H4 (having the structure H2NNH2), and its derivatives have been used as rocket fuels. Draw the Lewis electron-dot formula for the hydrazine molecule. Describe the geometries expected about the nitrogen atoms in this molecule. Why would you expect hydrazine to be basic? Which substance, NH3 or N2H4, would you expect to be more basic? Why? Write the chemical equation in which hydrazine reacts with hydrochloric acids to form the salt N2H5Cl. Consider the positive ion of this salt. How does its basic character compare with that of NH3 and N2H4? Explain.arrow_forward
- For oxyacids, how does acid strength depend on a. the strength of the bond to the acidic hydrogen atom? b. the electronegativity of the element bonded to the oxygen atom that bears the acidic hydrogen? c. the number of oxygen atoms? How does the strength of a conjugate base depend on these factors? What type of solution forms when a nonmetal oxide dissolves in water? Give an example of such an oxide. What type of solution forms when a metal oxide dissolves in water? Give an example of such an oxide.arrow_forwardIn the following net ionic reaction, identify each species as either a Brnsted-Lowry acid or a Brnsted -Lowry base: CH3COO(aq)+HS(aq)CH3COOH(aq)+S2(aq). Identify the conjugate of each reactant and state whether it is a conjugate acid or a conjugate base.arrow_forwardThe sec-butyl cation can react as both a Brnsted-Lowry acid (a proton donor) and a Lewis acid (an electron pair acceptor) in the presence of a watersulfuric acid mixture. In each case, however, the product is different. The two reactions are as follows: (a) In which reaction(s) does this cation react as a Lewis acid? In which reaction(s) does it react as a Brnsted-Lowry acid? (b) Write Lewis structures for reactants and products and show by the use of curved arrows how each reaction occurs.arrow_forward
- Hydrazine (N2H4) is like CO32 in that it is a polyprotic base (Kb1 = 85 107 and Kb2 = 8.9 1016). The two conjugate acids are N2H5+ and N2H62+. What is the expected pH of a 0.025 M solution of N2H4? (a) 3.83 (b) 8.32 (c) 10.16arrow_forwardRank the compounds in each of the following groups in order of increasing acidity or basicity, as indicated, and explain the order you assign. (a) acidity: HCI, HBr, HI. (b)basicity: H2O, OH-, H-, CI-. (c) basicity: Mg(OH)2, Si(OH)4, ClO3(OH) (Hint: Formula could also be written as HCIO4). (d) acidity: HF, H2O, NH3, CH4arrow_forwardFor conjugate acidbase pairs, how are Ka and Kb related? Consider the reaction of acetic acid in water CH3CO2H(aq)+H2O(l)CH3CO2(aq)+H3O+(aq) where Ka = 1.8 105 a. Which two bases are competing for the proton? b. Which is the stronger base? c. In light of your answer to part b. why do we classify the acetate ion (CH3CO2) as a weak base? Use an appropriate reaction to justify your answer. In general, as base strength increases, conjugate acid strength decreases. Explain why the conjugate acid of the weak base NH3 is a weak acid. To summarize, the conjugate base of a weak acid is a weak base and the conjugate acid of a weak base is a weak acid (weak gives you weak). Assuming Ka for a monoprotic strong acid is 1 106, calculate Kb for the conjugate base of this strong acid. Why do conjugate bases of strong acids have no basic properties in water? List the conjugate bases of the six common strong acids. To tie it all together, some instructors have students think of Li+, K+, Rb+, Cs+, Ca2+, Sr2+, and Ba2+ as the conjugate acids of the strong bases LiOH, KOH. RbOH, CsOH, Ca(OH)2, Sr(OH)2, and Ba(OH)2. Although not technically correct, the conjugate acid strength of these cations is similar to the conjugate base strength of the strong acids. That is, these cations have no acidic properties in water; similarly, the conjugate bases of strong acids have no basic properties (strong gives you worthless). Fill in the blanks with the correct response. The conjugate base of a weak acid is a_____base. The conjugate acid of a weak base is a_____acid. The conjugate base of a strong acid is a_____base. The conjugate acid of a strong base is a_____ acid. (Hint: Weak gives you weak and strong gives you worthless.)arrow_forward
- Follow the directions of Question 65 for the following bases: (a) SO32- (b) CHO2- (c) NO2-arrow_forwardIn each of the following acid-base reactions, identify the Brnsted acid and base on the left and their conjugate partners on the right. (a) HCO2H(aq) + H2O() HCO2(aq) + H3O+(aq) (b) NH3(aq) + H2S(aq) NH4+(aq) + HS(aq) (c) HSO4(aq) + OH(aq) SO42(aq) + H2O+()arrow_forward2. The molecule whose structure is illustrated here is amphetamine, a stimulant Which description best fits this molecule? (Note: There may be more than one answer.) Brønsted acid Lewis acid Brønsted base Lewis basearrow_forward
- Chemistry by OpenStax (2015-05-04)ChemistryISBN:9781938168390Author:Klaus Theopold, Richard H Langley, Paul Flowers, William R. Robinson, Mark BlaserPublisher:OpenStaxChemistry: Matter and ChangeChemistryISBN:9780078746376Author:Dinah Zike, Laurel Dingrando, Nicholas Hainen, Cheryl WistromPublisher:Glencoe/McGraw-Hill School Pub CoIntroductory Chemistry: An Active Learning Approa...ChemistryISBN:9781305079250Author:Mark S. Cracolice, Ed PetersPublisher:Cengage Learning
- Chemistry & Chemical ReactivityChemistryISBN:9781133949640Author:John C. Kotz, Paul M. Treichel, John Townsend, David TreichelPublisher:Cengage LearningChemistry: The Molecular ScienceChemistryISBN:9781285199047Author:John W. Moore, Conrad L. StanitskiPublisher:Cengage Learning