Name
Date
K
Naming Binary Covalent Compounds
Binary covalent compounds come from the combination of two nonmetals (or a
nonmetal and a metalloid). These compounds do not involve ions; as a result, they
have a slightly different naming system. Chemists use prefixes to indicate the number
of atoms in each compound. The prefixes are listed in the table below:
# of Atoms
1
2
3
4
5
6
Prefix
Mono
Di
Tri
Tetra
Penta
Hexa
Hepta
Octa
Nona
Deca
7
8
9
10
When naming binary covalent compounds, the first element name is given followed by
the second element with an "ide" ending. The first element gets a prefix when there is
more than one atom in the compound * The second element ALWAYS gets a prefix.
Here are some examples:
Compound
Name
NO*
N2O
N02*
N203
N204
N205
Nitrogen Monoxide
Dinitrogen Monoxide
Nitrogen Dioxide
Dinitrogen Trioxide
Dinitrogen Tetraoxide
Dinitrogen Pentaoxide -
* Notice that the prefix "mono" is omitted in these cases
Prefixes are necessary when naming covalent compounds because the atoms can
combine in any whole number ratio. N2O, for example, cannot simply be cal ed
'
oxide " because there are several other compounds that contain mtrogen
Wemust specify that there are two nitrogen atoms bonded to a single oxygen
atom.
When dealing with ionic compounds, there is only one way for a cation and anlon to
combine toform a neutral compound. As a result, there is no need to use prefixes,
is why CaCI2 is called "calcium chloride," rather than "calcium d,chlor,de.
Writing the Names of Covalent Compounds
1) List the name of the first element in the formula.
2) List the second element and add the -ide suffix.
3) Use Greek prefixes to indicate the number of each atom in the formula.
• Exception; do not use mono- for the first element in the name.
•
The o or a at the end of the Greek pre-fix is usually dropped when the element
name begins with a vowel
Example: Write the name for N2S4
1) List the name of the first element in the formula.
nitrogen
2} list the second element and add the -ide suffix.
nitrogen sulfide
3) Use Greek prefixes to indicate the number of each atom in the formula.
• See your textbook or lecture notes for a table of the Greek prefixes.
nitrogen
sulfide
dinitrogen tetrasulfide
Exception; do not use mono- for the first element in the name.
Not applicable in this example
The o or o at the end of the Greek pre-fix is usually dropped when the element
name begins with a vowel
Not applicable in this example
Example: Write the name for S03
1) List the name of the first element in the formula.
sulfur
?) List the second element and add the -ide suffix.
sulfur oxide
3) Use Greek prefixes to indicate the number of each atom in the formula.
sulfur
oxide
sulfur trioxide
•
Exception: oo not use mono- for the first element in the name.
• NOTE, we did not write monosulfur because of this rule!
Example: Write the name for CO
1) List the name of the first element in the formula.
carbon
?) List the second element and add the -ide suffix,
carbon oxide
3} Use Greek prefixes to Indicate the number of each atom ,n the formula.
carbon
_ oxide
carbon monoxide
.
.
Exception: do not use mono- for the first element in the name
. NOTE we did not write monocarbon because of this rule.
The o or o at the end of the Greek pre-fix is usually dropped when the e,ement
name begins with a vowel
. NOTE, we did not write monooxygcn because of this rule.