Covalent nomenclature is significantly less complicated than ionic
nomenclature. When naming binary covalent compounds, you should be familiar
with the following prefixes:
One: Mono- Two: Di-
Three: Tri- Four: Tetra-
Five: Penta- Six: Hexa-
Seven: Hepta-Eight: Octa-When naming the compound, how many of each atom present is represented by
the appropriate prefix. Si 3 N 6 would be trisilicon hexanitride, and C 4 F 8 would be
tetracarbon octafluoride. The only exception to this rule is that if the first
element has only one atom present, you do not use the mono prefix. CO would
be carbon monoxide, not monocarbon monoxide.
The easiest way to determine whether you are using ionic nomenclature rules or
covalent nomenclature rules is by determining the type of bond first. Metals and
nonmetals combine to form ionic bonds, while two nonmetals combine to form
covalent bonds.
The Metallic Bond
As you’ve probably guessed, a metallic bond results when two metals bond. For
example, the copper atoms that make up a copper wire are joined by metallic
bonds. In metallic bonding, the metal atoms donate valence electrons to become
cations. These valence electrons are not directly transferred to another atom as
they are in ionic bonding. Instead, they move about freely throughout the
sample, producing an attractive force that keeps the metal cations in place. Often
the behavior of these free electrons is referred to as a “sea of mobile electrons.”
Because of the motions of the free electrons, metals are characteristically good
conductors of electricity and heat.