Chapter 3 Section 3.5 Guideline #2 Tasks #3 & #4 Study Guide
††††††††Binary Molecular Compounds

 Binary Molecular compounds are explained in Chapter 3 Section 3.5 Guideline #2.


1.      Both elements are nonmetals attached by covalent bonds. These bonds may be single, double, or triple covalent (explained in Chapter 6)


†††††††††††††††††††††††††††††††††† †††††††††††††††

2.      Due to the covalent bonding there are many ratios of the same two elements making many different compounds.  For this reason, the chemist states how many atoms of each element are present in the chemical formula in the formal name of the compound.

3.      Prefixes are attached to each element to indicate how many atoms are present in the formula

4.      The elementís name that is shown first in the chemical formula is written first using the proper prefix to indicate how many atoms of that element are contained in one molecule of the compound.  If there is only one atom of that element it is often found without the prefix mono.  If you leave the prefix off then it is understood that you mean mono.

5.      The elementís name which is written second in the chemical formula is written second in the chemical name, but in addition to the prefix indicating how many, the suffix of the elementís name is changed to -ide

carbon becomes carbide                             chlorine becomes chloride

sulfur becomes sulfide                                oxygen becomes oxide

hydrogen becomes hydride                        nitrogen becomes nitride 


Below is the table of prefixes that you use in Binary Molecular Compounds

MONO         =          ONE                          HEXA          =        SIX

DI                =          TWO                         HEPTA        =         SEVEN

TRI              =          THREE                      OCTA          =         EIGHT

TETRA         =          FOUR                         NONA        =         NINE

PENTA         =          FIVE                           DECA         =         TEN

 Therefore, the following formulas of binary compounds would be written:

CCl4     carbon tetrachloride                                                     


SO2      sulfur dioxide

SO3      sulfur trioxide


CO2      carbon dioxide

CO      carbon monoxide


N2O††††† Dinitrogen oxide(also nitrous oxide-laughing gas)

NO††††††† Nitrogen oxide††(also known as Nitric oxide)

NO2†††††† Nitrogen dioxide††

N2O3      dinitrogen trioxide

N2O5      dinitrogen pentoxide


 BH3       boron trihydride
Tetraboron decoxide

We use common names for NH3, and H2O, as shown Guideline #4.

What would be their correct binary molecular names?

AmmoniaNH3 would be Nitrogen trihydride

Water H2O would be Dihydrogen monoxide

Sometimes they call water DHMO or in fuel they call water vapor HHO

As a spoof, the chemist at Dupont on the Delaware River created web site alerting you to the toxicity of a compound DHMO Visit this site!

Methane, CH4, is the organic name for CH4, (Chapter 12) what would its inorganic name be?††† Carbon tetrahydride