The chemical forces of attraction that hold atoms or ions
together in chemical compounds
are called chemical bonds. All chemical bonds
result from the simultaneous attraction of one or more electrons by two or more
nuclei. In unit 4 we introduced
to you two types of chemical bonding.
Another type of bond is one that is observed between
nonmetals is covalent
bond. Specifically, if the bond is between identical nonmetals, then the
bond is a nonpolar covalent bond.
When a substance contains atoms of both
metals and nonmetals, the electrons are naturally more attracted to the
nonmetals. The nonmetals become negatively charged
ions and the metals naturally become positively
charged ions. (NOTE: The
number of electrons that is gained or lost by the nonmetal and the metal is
determined by the octet
rule.) An attractive force exists between the oppositely charged
ions. The force that keeps
the ions held together is the chemical bond called the ionic
Ionic bonding requires a transfer
of electrons from a metal to a nonmetal, a process that forms
Once these ions are formed, they arrange themselves into a 3-dimensional crystal
in the solid state.
Take a look at the arrangement of ions in sodium chloride.
Let's look at the formation of ionic bonds in details in
the next section.