General ---------Biology ------------------Online------------------   ----wilcox@sunline.net Ch.  2 :  The Chemical Context of Life

Atoms combine ("react") to form molecules by sharing each others electrons.

The result on this sharing arrangement is tension.  (Recall that opposites attract and like charges repel.)  Assignment: Explain, in one sentence, the tension in the gas molecule above. Do not turn this sentence in, but bring it to class a be prepared to read it.  (In explaining this, you will be explaining the "nature of a chemical bond" and where in the bond lies the energy, i.e. the "calories.") 
________________________________________________________________

________________________________________________________________.

The shared electrons create a "chemical bond," called a covalent bond.  There is energy stored in covalent bonds, and the source of this energy is the tension.  To see what
happens when the energy in covalent bond is broken, click Hindenburg Disaster.

Summary: You should understand 

• atoms react to form molecules by sharing outer shell electrons
• these shared electrons form "chemical bonds" between the atoms
• these chemical bonds are called "covalent bonds"
• covalent bonds store energy (calories)
• the source of this energy is the tension between attraction and repulsion