Organic Chemistry Study Guide

Key Concepts, Problems, and Solutions

Robert J. Ouellette, J. David Rawn

• Éditeur: Elsevier
• Année: 2014
• ISBN:
  9780128018644
• Sujet: Physical Sciences
• Sous-sujet: Organic Chemistry

Organic Chemistry Study Guide: Key Concepts, Problems, and Solutions features hundreds of problems from the companion book, Organic Chemistry, and includes solutions for every problem. Key concept summaries reinforce critical material from the primary book and enhance mastery of this complex subject.

Organic chemistry is a constantly evolving field that has great relevance for all scientists, not just chemists. For chemical engineers, understanding the properties of organic molecules and how reactions occur is critically important to understanding the processes in an industrial plant. For biologists and health professionals, it is essential because nearly all of biochemistry springs from organic chemistry. Additionally, all scientists can benefit from improved critical thinking and problem-solving skills that are developed from the study of organic chemistry.

Organic chemistry, like any "skill", is best learned by doing. It is difficult to learn by rote memorization, and true understanding comes only from concentrated reading, and working as many problems as possible. In fact, problem sets are the best way to ensure that concepts are not only well understood, but can also be applied to real-world problems in the work place.

• Helps readers learn to categorize, analyze, and solve organic chemistry problems at all levels of difficulty
• Hundreds of fully-worked practice problems, all with solutions
• Key concept summaries for every chapter reinforces core content from the companion book

1

Structure and Bonding in Organic Compounds

Keys to the Chapter

Atomic Structure and Properties

Two periodic trends are important to understanding the physical and chemical properties of organic compounds. They are electronegativity and atomic radius.

The electronegativity scale is an index of the attraction of an atom for an electron. It increases from left to right in a period and from bottom to top in a group of the periodic table. The order of electronegativities for the three most common elements in organic molecules, excluding hydrogen, is C < N < O. Their electronegativity values differ by 0.5 between neighboring elements in this part of the second period. There is a more pronounced difference between second and third period elements. Thus, fluorine and chlorine differ by 1.0, as do oxygen and sulfur. The order of the electronegativity values of the halogens is I < Br < Cl.

Ionic and Covalent Bonds

There are two main classes of bonds. Ionic bonds predominate in inorganic compounds, but covalent bonds are much more important in organic chemistry. When positive and negative ions combine to form an ionic compound, the charges of the cations and anions must be balanced to give a neutral compound. For ionic compounds, the cation is named first and then the anion. Thus, ammonium sulfide contains (NH₄)₂ and S²⁻. Two ammonium ions are required to balance the charge of one sulfide ion, so the formula of ammonium sulfide is (NH₄)₂S. Parentheses enclose a polyatomic ion when a formula unit contains two or more of that ion, and the subscript is placed outside the parentheses.

A covalent bond forms when two nuclei are simultaneously attracted to the same pair of electrons. Carbon usually forms covalent bonds to other elements. The stability of Lewis structures is attributed to the octet rule that states that second row elements tend to form associations of atoms with eight electrons (both shared and unshared) in the valence shell of all atoms of the molecule.

One or more pairs of electrons can be shared between carbon atoms. ...