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 element’s 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 element’s 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 element’s 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
B₄O₁₀ Tetraboron decoxide

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

What would be their correct binary molecular names?

Ammonia NH₃ 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 http://www.dhmo.org Visit this site!

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