1. Covalent Nomenclature
Naming Molecular Compounds

2. Review How do we identify ionic formulas?
Ionic formulas start with metals (or NH4+1)
How do we identify covalent formulas?
Covalent formulas contain only non-metals or metalloids.
How do we name ionic compounds?
Identify the compound as binary or ternary.
Identify the metal as fixed charge or variable charge.
If the compound is binary, ends in –ide.
If the compound is ternary, name the anion appropriately.

3. Naming Molecular Compounds
All the molecular compounds you’ll be asked to name are binary.
Molecular compounds w/ more than 2 elements are usually organic.
Organic compounds have their own special naming system.
Prefixes indicate the number of each atom in the molecule:
mono = 1
di = 2
tri = 3
tetra = 4
penta = 5
hexa = 6
hepta = 7
octa = 8
nona = 9
deca = 10

4. Naming Molecular Compounds
Prefix for first element in compound.
Omit if it’s “mono”.
Name first element.
Prefix for second element in compound.
Give stem of second element followed by suffix –ide.
Examples:
CO = carbon monoxide
CO2 = carbon dioxide
N2O = dinitrogen monoxide

5. Details and Exceptions
If the last letter of the prefix and the first letter of the element are both vowels, drop the last letter of the prefix.
CO = carbon monoxide, not carbon monooxide
N2O5 = dinitrogen pentoxide, not dinitrogen pentaoxide
Some compounds are known only by their common names
H2O = water
NH3 = ammonia
CH4 = methane

6. Writing Formulas From Names
Write symbols in the same order they appear in the name.
Use prefixes to determine subscripts.
Metalloids are not metals.
Compounds that start with metalloids are named as molecular compounds.

7. Naming Molecular Compounds
What are the names of the following molecular compounds?
NO2
SO3
SiO2 NO
P2O5
S4N4
nitrogen dioxide
sulfur trioxide
silicon dioxide
nitrogen monoxide
diphosphorus pentoxide
tetrasulfur tetranitride

8. Writing Formulas From Names
What are the formulas of the following molecular compounds?
carbon tetrachloride
phosphorus trichloride
selenium dibromide
dinitrogen tetroxide
sulfur dioxide
xenon tetrafluoride
diantimony trioxide
CCl4
PCl3
SeBr2
N2O4
SO2
XeF4
Sb2O3