4. Electron Sharing and      Covalent Bonds   Previous PageNext Page

What is a covalent chemical bond? In a simple wooden model, two balls representing atoms are connected by a stick symbolizing the bond. What is the "stick" that holds the atoms together in a real molecule? How does a pair of electrons keep two atoms from flying apart? Just as important, how many bonds can a particular type of atom form with other atoms, and in what directions in space? Only when we can answer these questions can we understand how molecules are constructed and how they behave.

As we saw with the H2 molecule in Chapter 2, a bond between two atoms is formed by the sharing of a pair of electrons between the atoms. This is illustrated on the right. The bonding pair of electrons spends most of its time between the two atomic nuclei, thereby screening the positive charges from one another and enabling the nuclei to come closer together than if the bonding electrons were absent. The negative charge on the electron pair attracts both nuclei and holds them together in a bond.

  Page 1 of 54 HomeGlossary