2.3 Naming Molecular Compounds
PRE-HEALTH PREP
Naming Molecular Compounds
Naming molecular compounds is generally easier than naming ionic compounds. A molecular compound is composed of two or more nonmetals, and in this lesson you will specifically learn how to name molecular compounds comprised of exactly two nonmetals (known as binary molecular compounds). There is no worrying about oxidation states and roman numerals as with some ionic compounds. There is simply a numerical prefix added before the name of each element to indicate how many atoms of that element are in a molecule. The rules and numerical prefixes are summarized in the tables below.
Rules for Naming Molecular Compounds
| 1. Give the numerical prefix of the first element (omit if only one--mono). |
| 2. Name the first element. |
| 3. Give the numerical prefix for the second element. |
| 4. Name the second element with the -ide suffix. |
| Numerical Prefixes | |
|---|---|
| 1 | mono |
| 2 | di |
| 3 | tri |
| 4 | tetra |
| 5 | penta |
| 6 | hexa |
| 7 | hepta |
| 8 | octa |
| 9 | nona |
| 10 | deca |
Naming Molecular Compounds Examples
Below the names of several binary molecular compounds are summarized. Note that when there is only one of the 1st element the prefix mono is omitted from the name, but when there is only one of the 2nd element the prefix mono is included.
| Chemical Formula | 1st Prefix | 2nd Prefix | |||
|---|---|---|---|---|---|
| P4O10 | tetra | phosphorus | deca | oxide | tetraphosphorus decoxide |
| N2O5 | di | nitrogen | penta | oxide | dinitrogen pentoxide |
| SF6 | n/a | sulfur | hexa | fluoride | sulfur hexafluoride |
| N2O | di | nitrogen | mono | oxide | dinitrogen monoxide |
| CO | n/a | carbon | mono | oxide | carbon monoxide |
Naming Molecular Compounds Practice
Hover over the boxes below to reveal the name/formula.