Organic chemistry is often referred to as the chemistry of life because biological compounds such as DNA, proteins, and carbohydrates are themselves organic molecules. In this chapter, we examine some of the bonding characteristics of these and other organic molecules, which are constructed primarily from carbon, hydrogen, nitrogen, and oxygen.

On completing Chapter 1 you should be able to:

1. Distinguish organic compounds from inorganic ones.
2. Explain the advantages that come from carbon being the basis of organic molecules.
3. Describe the basic structure of an atom and understand that the vast majority of its volume is taken up by electrons.
4. Determine the ground state electron configuration of any atom in the first three rows of the periodic table and distinguish valence electrons from core electrons.
5. Define bond length and bond energy and understand how these two quantities depend on the number of bonds between a given pair of atoms.
6. Draw the Lewis structure of a species, given only its connectivity and total charge.
7. Differentiate between a nonpolar covalent bond, a polar covalent bond, and an ionic bond, and distinguish a covalent compound from an ionic compound.
8. Assign the formal charge to any atom in a molecular species, given only its Lewis structure.
9. Describe what a resonance structure is and explain the effect that resonance has on a species’ stability.
10. Draw all resonance structures of a given species, as well as its resonance hybrid, and determine the relative stabilities of resonance structures.
11. Draw and interpret Lewis structures, condensed formulas, and line structures.
12. Explain why functional groups are important and identify functional groups that are common in organic chemistry.

Organic chemistry is often called “the chemistry of life” because certain types of compounds, and the reactions they undergo, are suitable to sustain life, while others are not. What are the characteristics of such compounds and what advantages do those compounds afford living organisms? Here in Chapter 1 we begin to answer these questions.

We review several aspects of atomic and molecular structure typically covered in a general chemistry course, including ionic and covalent bonding, the basics of Lewis dot structures, and resonance theory. We then begin to tighten our focus on organic molecules, presenting various types of shorthand notation that organic chemists often use and introducing you to functional groups commonly encountered in organic chemistry.

Toward the end of this chapter, we shift our focus to examining specific classes of biomolecules: amino acids, monosaccharides, and nucleotides. Not only does such a discussion provide insight into the relevance of organic chemistry to biological systems, but it also reinforces specific topics covered in the chapter, such as functional groups.