Binary Molecular Compounds

When two non-metal elements combine, they form a binary molecular compound. These compounds combine by forming a covalent bond between non-metallic elements. Some of the common examples of binary compounds include H₂O, NaCl, MgCl, CO, etc. It is very difficult to name binary molecular compounds as they form covalent bonds. As they do not form ionic bonds, it becomes difficult to name them according to their electrical neutrality. These binary molecular compounds may have a generic name as well as systemic names in Chemistry. We generally tend to use the common names for most of the compounds, like water, salt, etc. There are a few rules for naming binary molecular compounds according to the International Union of Pure and Applied Chemistry (IUPAC). Let us go through the rules for naming binary molecular compounds.

What are Binary Molecular Compounds

When two non-metallic elements combine they are called binary molecular compounds. They share their electrons using covalent bonds. They can exist in three forms under standard temperature and pressure (STP). These forms are solid, liquid and gaseous. The binary molecular compounds have low melting and boiling points.

Rules for Naming Binary Molecular Compounds

As explained above, binary molecular compounds are made from two different non-metal elements. There are a few basic rules for naming binary molecular compounds. Let us have a look at these rules.

Rule # 1: When naming binary molecular compounds the element with the lowest group number is written first followed by the element with a higher group number. The exception to this rule is only when the compound contains an oxygen and a halogen. In this case, the name of the halogen is written first when naming the binary compound.

Rule # 2: When both the elements belong to the same group, the element with the higher period number is written before the one with the lower period number.

Rule # 3: When writing the name of the second element, a suffix -ide is added to the name.

Rule # 4: The number of atoms in each of the non-metal elements present in the chemical formula of the compound are indicated using Greek prefixes. The exception to this rules is the prefix mono is generally not used when the compound contains just one atom. The following is the list of prefixed used when naming binary compounds.

• 1 ~ mono-
• 2 ~ di-
• 3 ~ tri-
• 4 ~ tetra-
• 5 ~ penta-
• 6 ~ hexa-
• 7 ~ hepta
• 8 ~ octa-
• 9 ~ nano
• 10 ~ deca-

One is required to use these rules for naming binary molecular compounds. Let us go through the binary molecular compounds list.

Binary Molecular Compounds List

The following table contains a few examples of binary molecular compounds. You can go through the following list and understand the rules for naming binary molecular compounds clearly.

Binary Molecular Compounds List
Compound	Systemic Name
CO2	Carbon dioxide
CO	Carbon monoxide
Cbr4	Carbon tetrabromide
Ccl4	Carbon tetrachloride
As2O5	Diarsenic pentoxide
H2S	Dihydrogen monosulfide
H2O	Dihydrogen monoxide
N2O	Dinitrogen monoxide
N2H4	Dinitrogen tetrahydride
N2O4	Dinitrogen tetraoxide
P2O5	Diphosphorus pentoxide
S2F10	Disulfur decafluoride
Icl4	Iodine trichloride
NO2	Nitrogen dioxide
NO	Nitrogen monoxide
NF3	Nitrogen trifluoride
NH3	Nitrogen trihydride
NI3	Nitrogen triiodide
Pcl5	Phosphorous pentachloride
Pcl3	Phosphorous trichloride
PH3	Phosphorous trihydride
Pbr5	Phosphorus pentabromide
SeF6	Selenium hexafluoride
SiO2	Silicon dioxide
SO2	Sulfur dioxide
SF6	Sulfur hexafluoride
SO3	Sulfur trioxide

This was some information related to binary molecular compounds. There are different binary molecular compounds made from the combination of non-metal elements. Hope you have understood the rules for binary molecular compounds nomenclature.