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Naming chemical compounds

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Tutor: Lana


Naming chemical compounds

In a nutshell

Compounds are formed when atoms of different elements undergo a chemical reaction and form chemical bonds. There are five main rules when naming a compound. This lesson will go over these rules, with examples.

Rule 1

If a compound is made up of only two elements, then the compounds name will end in -ide. 


Lithium chloride (LiClLiCl​) is composed of only lithium and chlorine atoms.   

Rule 2

The first part of the compounds name must be the element that is furthest to the left in the periodic table. 


Potassium iodide (KIKI) has potassium at the start of the name since potassium is in Group 11​.

Rule 3

Compounds will end with the suffixes -ite or -ate if there are three or more elements present, and one of those elements is oxygen. 


Potassium iodate (KIO3KIO_3​) is made up of potassium, iodine and oxygen atoms.

The -ite suffix can be found in compounds like sodium sulfite (Na2SO3Na_2SO_3and lithium nitrite (LiNO2LiNO_2).

Rule 4 

In some instances, the name of the compound can contain prefixes which show how many atoms of a given element are present.


A prefix is a group of letters added to the start of an element. Prefixes are used to specify how many atoms of a given element are present in a molecule of a compound.

​The table below shows some of the most common prefixes.


Number of atoms












A carbon monoxide molecule (COCO​) is composed of one carbon atom and one oxygen atom, therefore it contains the prefix mono-. 

Carbon dioxide (​CO2CO_2​) is made up of one carbon atom bonded to two oxygen atoms, therefore it contains the prefix di-.

Carbon tetrachloride (​CCl4CCl_4​) has four chloride atoms in each molecule.

Rule 5

Acids composed of hydrogen and one other element will have a “hydro-“ prefix and an “-ic’ suffix. 


Hydrochloric acid has the suffix -ic.

Acids containing oxygen atoms can end with the suffix “-ous” or “-ic”. 


Phosphoric acid and nitrous acid.

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FAQs - Frequently Asked Questions

How do you name a compound made of two elements?

Why do certain compounds end in -ate or -ite?

Why are prefixes used when naming compounds?


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