How to Name Covalent Compounds

Naming covalent compounds involves the use of Greek prefixes. They are listed in the table to the right. The prefixes are used to indicate the amount of each atom in the compound. The first element never uses the prefix mono-, but does use all others. The second element uses all prefixes and ends in -ide ending, as it would in an ionic compound.

Example #1: CO2 is named carbon dioxide
Example #2: N2O is named dinitrogen monoxide

Step by step example: Write the name for N2O5

Description of Action	Action
1. Identify the prefix that corresponds to the subscript following the first symbol. NEVER USE THE PREFIX MONO- BEFORE THE FIRST ELEMENT'S NAME!	di- There are 2 nitrogen in N2O5 so the prefix di- is used.
2. Add the name of the first element to the end of the prefix.	dinitrogen
3. Write the prefix for the subscript that follows the second element. You must leave a space between the first name and the second name.	dinitrogen penta- There are 5 oxygen in N2O5 so the prefix penta- is used.
4. Attach the root name of the second element to the second prefix.	dinitrogen pentox The a is dropped because the first letter of the second element is a vowel.
5. Add “-ide” to the end of the second element’s root name.	dinitrogen pentoxide

Covalent Prefixes
1	mono-
2	di-
3	tri-
4	tetra-
5	penta-
6	hexa-
7	hepta-
8	octa-
9	nona-
10	deca-

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