Organic Chemistry 1 Chapter 1 Structure and Bonding – Assignment Quiz 2 PDF

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This document contains the questions and answers. The questions on the document appear in assignment 2 for chapter 1 for organic chemistry 1. Some of these questions also appear on the weekly quiz and may appear on the exam. It is a great place to start to review for assignments, quizzes, and exams...

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1/9 Organic Chemistry 1 Chapter 1 Structure and Bonding – Assignment/Quiz 2 1. Which statement correctly describes resonance structures? a. Resonance structures are isomers of the same species that differ in the placement of atoms. b. Resonance structures are Lewis structures for the same species that have a different total number of electrons. c. Resonance structures are Lewis structure for the same species that different in the placement of electrons. Resonance structures differ in the position of π bonds and nonbonded electron pairs (lone pairs). 2. Match each geometry with the correct bond angle. 

Linear – 180°

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Trigonal planar – 120°

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Tetrahedral – 109.5°

3. Correctly order the steps necessary to determine the geometry around a given atom. Place the first step at the top of the list and the last step at the bottom of the list. 

3 Match the number of groups with the associated geometry.

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2 Count groups around a given atom.

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1 Draw a valid Lewis structure.

2/9 4. Which of the following statements correctly describe the procedure for drawing a Lewis structure? (Select all that apply.) a. A single bond, which represents 2 electrons, should be placed between every two atoms. b. Nonbonding electrons should be excluded from the Lewis structure. Nonbonding electrons are always included in a Lewis structure. c. For a neutral molecule the sum of the number of valence electrons for each atom gives the number of electrons used in the Lewis structure. d. Halogen atoms are usually places at the center of the structure. Halogen atoms are usually placed at the periphery of the structure because they usually form one bond. e. An electron is added to the total count for each negative charge on the species. 5. Multiple bonds only contain one sigma bond. 6. Explain why CO2 is a nonpolar molecule. a. CO2 contains polar bonds but is unsymmetrical in shape, which makes it nonpolar. b. The individual bonds in CO2 are nonpolar so the molecule is nonpolar. c. CO2 is linear and therefore the individual bond dipoles cancel to give no net dipole.

3/9 7. Select all statements that correctly describe the typical number of covalent bonds formed by common neutral atoms. a. Atoms with 5 valence electrons typically form 5 covalent bonds. Atoms with 5 valence electrons typically form 3 bonds (8 – 5 = 3 bonds). b. Atoms with 3 valence electrons typically form 3 covalent bonds. c. Atoms with 8 valence electrons do not typically form bonds. d. Atoms with 7 valence electrons typically form 1 bond. 8. Match each species with its correct description. 

Molecule – contains only covalent bonds.

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Compound – may contain either ionic or covalent bonds, or both. A compound may be ionic or covalent.

9. The charged oxygen atom in the structure shown has three lone pairs of electrons, which have not been included.

4/9 10. Which of the following steps are necessary to determine the geometry around a given atom? (Select all that apply.) a. Draw a valid Lewis structure. b. Estimate each bond length in the molecule. Bond lengths are not necessary to determine the geometry around a given atom. c. Match the number of groups with the associated geometry. d. Count the number of groups around a given atom. 11. As the number of shared electrons between two nuclei increases, the bond length _____ and the bond strength _____. a. Decreases, decreases b. Increases, increases c. Decreases, increases d. Increases, decreases 12. Isomers are _____ molecule(s) that have _____ molecular formula(s). a. Identical, different b. Different, the same

5/9 13. Arrange the steps involved in drawing a Lewis structure in the correct order. Place the first step at the top of the list and the last step at the bottom of the list. 

1 Count the valence electrons from all atoms, and place the atoms next to each other according to their usual bonding patterns.

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5 Assign formal charges to all atoms. Formal charges cannot be assignment before any of the other steps are complete.

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3 Place a bond between every pair of atoms and use the remaining electrons to fill octets with lone pairs.

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4 Form multiple bonds if all electrons have been used and any atom does not have an octet.

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2 Add an electron for each negative charge and subtract one for each positive charge.

14. When interpreting skeletal structure of charged species, the number of lone pairs on a particular atom depends on the charge on that atom. Match each charge with the number of lone pairs present on the relevant atom. 

No lone pairs – A carbon atom with a positive charge (and 3 bonds)

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One lone pair – A carbon atom with a negative charge (and 3 bonds)

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Three lone pairs – An oxygen atom with a negative charge (and one bond)

15. An atom may lose or gain electrons to form an ion. If an ion has more electrons than its neutral form, it is called a(n) anion and it has a – charge. An ion with fewer electrons than its neutral form is a(n) cation and it has a positive charge.

6/9 16. Which of the following statements correctly describe a resonance hybrid? (Select all that apply.) a. A resonance hybrid has a single structure. b. A resonance hybrid is stabilized due to delocalization of electrons. c. Equivalent resonance forms contribute equally to the overall structure of a resonance hybrid. d. The true structure of a resonance hybrid is the structure of the most stable resonance contributor. A resonance hybrid is a composite of all contributing resonance forms. e. A resonance hybrid rapidly interconverts between the possible resonance forms. A resonance hybrid is one structure, it does not rapidly interconvert between resonance forms. 17. Electronegativity values _____ from left to right across a row and _____ down a column of the periodic table. a. Increase, decrease b. Increase, increase c. Decrease, decrease d. Decrease, increase 18. A bond dipole can be indicated with a(n) arrow that points towards the most electronegative element. The separation of charge can also be depicted with delta positive and delta – (or negative) signs to indicate the unequal sharing of electron density.

7/9 19. Which of the following can contain a maximum of 2 electrons? (Select all that apply.) a. The first shell b. A 2p orbital c. The 1s orbital d. The second shell The second shell can contain a maximum of 8 electrons (2s22p2). 20. Match each type of ion with the correct charge. 

Cation – Positivity charged

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Anion – Negatively charged

21. When interpreting skeletal structures of charged species, two general rules are useful. A charge on a carbon atom replaces _____ hydrogen atom(s), and the charge on any atom determines the number of covalent bonds and _____ electron pairs on that atom. a. 1; bonded b. 0; bonded c. 2; bonded d. 0; nonbonded e. 2; nonbonded f. 1; nonbonded

8/9 22. Match each element to the best description. 

31 15

– Contains 5 valence electrons

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32 16

– Contains 6 valence electrons and 10 core electrons

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16 8

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23 11

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12 6

P S

O – A group 6A element Na

– Contains 10 core electrons

C – Contains 4 valence electrons

23. Select all statements that correctly describe core and valence electrons. a. Core electrons are found in the inner shell orbitals. b. Valence electrons are more strongly held to the nucleus than core electrons. c. Valence electrons are the outermost electrons. d. Core electrons are typically responsible for the chemical properties of an element. 24. Match the convention used when indicating the polarity of a bond with its location. 

Tail of an arrow with a perpendicular line drawn through it – Positioned at the least electronegative element.

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Head of an arrow – Pointing toward the more electronegative element.

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δ+ – Positioned on the most electron deficient atom.

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δ- – Positioned on the most electron rich atom.

9/9 25. The structure shown represents an atom surrounded by 4 bonds drawn using the wedgedash format. The bond marked “a” is a bond _____ the plane, the bond marked “b” is _____ the plane, and the bond marked “c” is _____ the plane.

a. in, behind, in front of b. behind, in, in front of c. behind, in front of, in d. in, in front of, behind...