Structure of Molecules

Principles Module 5


  • Describe the major kinds of chemical bonds
  • Discuss the properties of carbon that make it well suited as the basis of life
  • Recognize the main classes of organic compounds and functional groups

Key points

  • covalent bonds form when atoms share electrons
    • single bonds represent 1 pair of shared electrons
    • double bonds form by 2 pairs of shared electrons
  • a molecule is formed by 2 or more atoms covalently bonded together
  • different atoms don’t share electrons equally, leading to polar bonds
  • ionic bonds form when a cation and anion combine
    • the result is an ionic compound
  • hydrogen bonds can hold polar covalent compounds together
  • chemical reactions occur when bonds are made or broken
    • reactants and products
    • reversibility
  • carbon compounds
  • functional groups

In-class activities

Today’s reading describes how geckos are able to ‘stick’ on many smooth surfaces through van der Waals interactions.

  • What does this claim mean?
  • How would you design an experiment to test this statement? In particular, what would you be testing, and what would your control(s) be?

After discussing this with your group, read the paper “Evidence for van der Waals adhesion in gecko setae” and compare your thinking to that of the scientists who demonstrated this for the first time.

Identify the functional groups in this list of molecules from the Krebs Cycle.