Docsity
Docsity

Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity


Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan


Guidelines and tips
Guidelines and tips

Chapter 2 homework assignment with answers, Assignments of Organic Chemistry

Homework set for Chapter 2 of Organic Chemistry

Typology: Assignments

2018/2019

Uploaded on 09/05/2024

oz-sports
oz-sports 🇺🇸

2 documents

1 / 4

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
1
Organic Chemistry I (CHE 311) Chapter 2: Molecular Representations1 Homework
—Instructor
Name: ________________________________________________________
1. (5 points) Draw the structure below with all the carbon and hydrogen atoms and lone
pairs.
2. (15 points) Identify all the functional groups in the molecules below by name (there are
at least 15, some are the same). Circle, draw a line, etc., from the name to identify the
groups present.
_____/20 points
1 David Klein. Organic Chemistry, 3rd Ed. John Wiley & Sons. (c) 2017.
pf3
pf4

Partial preview of the text

Download Chapter 2 homework assignment with answers and more Assignments Organic Chemistry in PDF only on Docsity!

Organic Chemistry I (CHE 311) Chapter 2: Molecular Representations^1 Homework —Instructor Name: ________________________________________________________

  1. (5 points) Draw the structure below with all the carbon and hydrogen atoms and lone pairs.
  2. (15 points) Identify all the functional groups in the molecules below by name (there are at least 15, some are the same). Circle, draw a line, etc., from the name to identify the groups present. _____/20 points (^1) David Klein. Organic Chemistry, 3rd (^) Ed. John Wiley & Sons. (c) 2017.
  1. (15 points) Draw the resonance structure(s) for the following molecule and its resonance hybrid; explain. Answer: Ozone has three lone pairs on the left oxygen; it has a formal charge of -1 (6ve-^ - 1 bond – 6 nbe-^ = -1). The middle oxygen atom has one lone pair; it has a formal charge of +1 (6ve- - 3 bonds – 2 nbe-^ = +1). The right oxygen atom has two lone pairs and a formal charge of zero (6ve-^ - 2 bonds – 4 nbe-^ = 0). The second structure forms as a curved arrow from the oxygen atom with three lone pairs moves to the single bond and another curved arrow moves electrons from the double bond to become a third lone pair on the right oxygen atom. The formal charge on the left oxygen is now zero, the central oxygen is still +1, and the right oxygen atom is now -1. The resonance hybrid shows dashed lines and single bonds between each pair of oxygen atoms. The central oxygen has a positive charge and the outer oxygen atoms both have partial negative charges.
  2. (10 points) In the structure below, there is one lone pair that is missing. Tell whether the lone pair is localized or delocalized and why. Answer: In order for the lone pair to participate in resonance, it must occupy a p-orbital. The p-orbital is already in use in the bond, so the lone pair occupies a hybrid orbital (sp).
  3. (55 points) Draw resonance structures for each of the following molecules. Tell which individual resonance structures are the most important and explain your reasoning. (continues next page) Answer: The oxygen atom has two lone pairs because its formal charge is zero (6ve-^ - 2 bonds – 4 nbe-^ = 0). The lone pairs are on an atom that is allylic to a bond, so a curved arrow moves a lone pair to the single bond at right and another curved arrow moves electrons in the bond to the carbon below. The resulting resonance structure has a formal charge of +1 for oxygen (6ve-^ - 3 bonds – 2 nbe-^ = +1) and -1 for the tertiary carbon with three bonds and one lone pair (4ve-^ - 3 bonds
  • 2 nbe-^ = -1). The left structure is most important because there are no formal charges and the octets are full. Answer: The nitrogen atom has one lone pair and a formal charge of zero (5ve-^ - 3 bonds – 2 nbe-^ = 0). The lone pair is vinylic (not allylic). The C=N bond is a bond between atoms of differing electronegativity, so one curved arrow moves the electrons in the bond to the N atom as a second lone pair. The resulting C has a formal charge of +1 (4ve-^ - 3

electrons from the adjacent bond toward the carbocation to form a new bond; the formal charge of +1 moves over to the carbon that is nearest the oxygen, forming the third resonance structure. The fourth structure is formed as one of the lone pairs is moved through a curved arrow to the C+, forming a double bond with O. The oxygen atom has a formal charge of +1 (6ve-^ - 3 bonds – 2 nbe- = +1). The structures all have one carbon with three bonds. The fourth structure has a positive formal charge on the most electronegative element, but all the octets are full on this structure. _____/30 points this page Total points on Ch. 2 Homework: _______________/