• If you are citizen of an European Union member nation, you may not use this service unless you are at least 16 years old.

  • You already know Dokkio is an AI-powered assistant to organize & manage your digital files & messages. Very soon, Dokkio will support Outlook as well as One Drive. Check it out today!


Chapter 2: The Chemical Basis of Life I

This version was saved 12 years, 5 months ago View current version     Revert to this version     Page history
Saved by Derek Weber
on September 3, 2011 at 3:53:00 am

Learning Objectives   

  • Understand subatomic structure, including how electron density affects an atom's ability to interact with another atom.
  • Quantify atomic mass using units such as Daltons and moles.
  • Relate atomic structure to the periodic table of the elements
  • Explain the discrete energy levels in which electrons orbit the nucleus of an atom.
  • Compare and contrast interactions known as covalent, ionic, and hydrogen bonding.
  • Explain the concept of electronegativity and how it contributes to the formation of polar and nonpolar covalent bonds.
  • Describe the properties of water that make it an ideal solvent for biological reactions.
  • Relate how the structure of water leads to hydrogen bonds. 
  • Describe how hydrogen bonding determines many properties of water.
  • Describe water’s cohesive and adhesive properties.
  • Explain the relevance of water’s unusual properties for living systems.
  • Understand the dissociation products of water. 
  • Explain the nature of acids and bases, and their relationship to the pH scale.
  • Understand the relationship between pH and hydrogen ion concentration, and explain how buffers maintain a stable environment  


Chapter Summary

A basic understanding of chemistry is necessary to the study of biology because the two are inexorably intertwined. Living organisms are chemical machines composed of molecules that continually undergo chemical reactions to become new molecules.


Atoms are composed of protons, neutrons, and electrons. Each subatomic particle has its effect on the chemical identity and interactivity of each element with all other elements. Formation of molecules from elements depends primarily on the tendency of electrons to occur in pairs, balance positive and negative charges, and fill the outermost shell. Chemical bonds result from trading or sharing electrons; shared bonds are stronger because they require the continued close proximity of atoms to one another.


Water, a simple but elegant molecule, predominates in living organisms and is unique in the life-giving characteristics stemming from its polar nature. Water clings to other polar molecules (adhesion), as well as itself (cohesion), by forming transient hydrogen bonds. These bonds absorb thermal energy; consequently the presence of water has a moderating effect on temperature changes. It is also a powerful solvent for other polar molecules and excludes nonpolar molecules, enabling the formation of biological membranes.


PowerPoint Presentation 

Chapter 2 PowerPoint (.pdf)


Virtual Lectures  

1. Electrons

2. Hydrogen Bonding 


** make sure to press OK when the LMS implementation screen appears.



1. Biologically Relevant Bond Types

2. Shell Model

3. Orbital Shapes

4. Valence Shells of the Common Elements

5. The Polarity of Water

6. Water as a Solvent

7. pH of Common Everyday Solutions 


Reading Assignments and Homework

In this chapter there are three section level eBook assignments (2.1-2.3).  Please check the availability dates for each.  There is also a homework due by 9/10.

Comments (0)