How to Name Chemical Compounds

Co-authored by Bess Ruff

Updated: March 29, 2019

Explore this Article Naming Ionic Compounds Naming Polyatomic Compounds Naming Covalent Compounds Article Summary Questions & Answers Related Articles References

Naming basic chemical compounds is essential if you want to succeed in chemistry, since the name of the compound clearly defines what it is. Each type of compound has its own rules for naming it. When naming compounds, you need to understand these different rules, as well as how to spot clues that will help you properly name the compounds. Follow this guide for some basic rules on how chemical compounds get their name, and how to apply names to compounds you are unfamiliar with.

Naming Ionic Compounds

  1. 1
    Know what makes a compound ionic. Ionic compounds contain a metal and a nonmetal. Refer to the periodic table of elements to see what categories the elements in the compound belong to.[1]
  2. 2
    Build the name. For a two element ionic compound, the naming is simple. The first part of the name is the name of the metal element. The second part is the name of the nonmetal element, with the suffix “-ide.”[2]
    • Here are some examples:
      • Al2O3. Al2 = Aluminium; O3 = Oxygen. So the name would be “aluminium oxide.”
      • FeCl3. Fe = Iron; Cl3 = Chlorine. So the name would be "iron chloride."
      • SnO2. Sn = Tin; O2 = Oxygen. So the name of this compound would be Tin Oxide.
  3. 3
    Recognize and name transition metals. Metals in the D and F blocks of the periodic table are known as transition metals. Their charge is written with a Roman numeral when writing out the compound name. This is because they can have more than one charge and make more than one compound.[3]
    • Example: FeCl2 and FeCl3. Fe = Iron; Cl2 = Chloride -2; Cl3 = Chloride -3. The names would be iron(II) chloride and iron(III) chloride.
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Method 1 Quiz

An ionic compound is composed of the elements sulfur and chromium. What is the name of the compound?

Not quite! Yes, the nonmetal element should get the -ide suffix in an ionic compound. But remember, with ionic compounds the metal element comes first! Try again...

Definitely not! The names of ionic compounds aren’t simply the names of both elements combined together without any change. For starters, the nonmetal element should have the end of its name replaced with the suffix -ide. Pick another answer!

Nope! You’ve got the suffix on the wrong element here! With ionic compounds, the -ide suffix should be appended to the name of the nonmetal element, not the metal element. Choose another answer!

Yes! Ionic compounds are composed of metal and nonmetal elements. The metal element always comes first in the name, and the nonmetal element comes second. Most crucially, be sure to replace the end of the name of the nonmetal element with the suffix -ide. Read on for another quiz question.

Naming Polyatomic Compounds

  1. 1
    Understand what a polyatomic compound is. These compounds are built off of groups of atoms that are covalently bonded together, and the entire group has a positive or negative charge.[4] You can do three basic things to polyatomic compounds, which will help you identify and understand these types of compounds:
  2. 2
    Memorize the most common ion groups. These are the basis for forming most polyatomic compounds. Listed in order of increasing negative charge, they are:
    • Hydroxide ion: OH-
    • Nitrate ion: NO3-
    • Hydrogen carbonate ion: HCO3-
    • Permanganate ion: MnO4-
    • Carbonate ion: CO32-
    • Chromate ion: CrO42-
    • Dichromate ion: Cr2O72-
    • Sulfate ion: SO42-
    • Sulphite ion: SO32-
    • Thiosulfate ion: S2O3<2-
    • Phosphate ion: PO43-
    • Ammonium ion: NH4+
  3. 3
    Build compound names based off the list. Associate whatever element(s) is attached to the group ion and name accordingly. If the element comes in front of the ion group, the name of the element is simply added to the beginning of the compound name.
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Method 2 Quiz

PO4 has an oxygen removed from the compound. What is the name of the new compound?

Absolutely! When you remove an oxygen from a compound, the suffix changes from -ate to -ite. In this case, phosphate becomes phosphite. Read on for another quiz question.

Nope! PO4 is already called phosphate. When you remove an oxygen from the compound, the charge should stay the same but the name will change. Choose another answer!

Not quite! This compound isn’t called phosphide. When a compound has an oxygen removed or added, it changes into either an -ite or -ate compound. Choose another answer!

Try again! This would be the name of the element by itself, rendered as P. A compound containing phosphorus, like PO4, would render the name of the element with a new suffix. Pick another answer!

Naming Covalent Compounds

  1. 1
    Understand a covalent compound. Covalent compounds are formed by two or more nonmetal elements. The name for the compound is based off how many atoms are present. The prefix attached is the Latin term for the number of molecules.
  2. 2
    Learn the prefixes. Memorize the prefixes for up to 10 atoms:
    • 1 atom – “Mono-“
    • 2 atoms – “Di-“
    • 3 atoms – “Tri-“
    • 4 atoms – “Tetra-“
    • 5 atoms – “Penta-“
    • 6 atoms – “Hexa-“
    • 7 atoms – “Hepta-“
    • 8 atoms – “Octa-“
    • 9 atoms – “Nona-“
    • 10 atoms – “Deca-“
  3. 3
    Name the compounds. Using the correct prefixes, name the new compound. You attach prefixes to any part of the compound that has multiple atoms.
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Method 3 Quiz

What is the name of the covalent compound C3Cl4?

Definitely not! With covalent compounds, a charge of 2 is represented by the prefix di-, but carbon here has a charge of 3. A charge of 3 is represented by the prefix tri-, but chlorine here has a charge of 4. Try another answer...

Correct! With covalent compounds, a charge of three is represented by the prefix tri-. A charge of four is represented by the prefix tetra-. Carbon becomes tricarbon and chloride becomes tetrachloride! Read on for another quiz question.

Nope! When naming covalent compounds, a charge of 1 is represented by the prefix mono-, but carbon here has a charge of 3. A charge of 2 is represented by the prefix di-, but chlorine here has a charge of 4. Choose another answer!

Not exactly! With the names of covalent compounds, a charge of 4 is represented by the prefix tetra, but carbon here has a charge of 3. A charge of 1 is represented by the prefix mono-, but chlorine here has a charge of 4. Pick another answer!

Community Q&A

Add New Question
  • Question
    What is the difference between ionic compounds and covalent compounds?
    Community Answer
    Ionic compounds occur between metals and non-metals. They exchange charges and end up with opposite ones. Covalent compounds occur between non-metals. They end up sharing the charges.
  • Question
    How do you name things like sulfuric acid and the other acids? How can you tell their formula based on the name?
    Community Answer
    There are two types of acids: those that contain oxygen, and those that do not. If they do not contain oxygen, take the name of the anion, add the prefix hydro, and end with -ic (then add "acid"). Example: HF, hydroflouric acid. To name acids with oxygen, find the name of the polyatomic ion, then change "-ate" to "-ic" or "-ite" to "-ous."
  • Question
    How do I identify elements of a compound that ends with -ate? For example, how do I know that carbonate is comprised of 1 Carbon and 3 oxygen atoms?
    Community Answer
    You have to memorize the common polyatomic compounds, like chromate ion and others.
  • Question
    What is a prefix and suffix?
    Community Answer
    A prefix is a beginning part of a word or term, a suffix is an end part. A prefix or a suffix generally has a specific meaning that it denotes - like the prefixes in Method 3 Step 2, which indicate the number of atoms.
  • Question
    When do I use stock system for naming chemical compounds?
    Community Answer
    The stock system is used for naming chemical compounds when the metal in the ionic compound is multivalent (meaning that it could have more than 1 possible charge in a bond), and thus it must be specified. However, you don't need to specify the charge of the metal in the compounds if it is in group 1 or 2 or if it's a monovalent transition metal (Al 3+, Zn 2+, Ag 1+, Cd 2+).
  • Question
    How do I find the names and formulas of compounds using a periodic table?
    Community Answer
    You can't find the names or formulas. You must memorize them instead.
  • Question
    Why is the mono not said in CO, like monocarbon monoxide?
    Community Answer
    It's implied.
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    • Also it is very important to realize that this doesn't apply to organic chemistry.
    • These rules are designed for people starting off in chemistry and science. Different rules apply when you reach advanced chemistry, for examples the rules of variable valency.
    • Of course, these rules all have many exceptions, for example, despite having a 2 at the end, CaCl2 is still simply called calcium chloride, NOT calcium dichloride as might be expected. (Calcium Chloride is an ionic compound so covalent prefixes are not used)

    Article SummaryX

    To name chemical compounds, first determine whether the compound is ionic, polyatomic, or covalent. If it is ionic, list the metal element first and then add the nonmetal element with the suffix “-ide.” This should result in a name like "aluminum oxide." To name covalent compounds, first memorize the prefixes that are used to indicate the number of atoms. For example, when there are 2 atoms, use the prefix "di" and before naming the rest of the compound. To learn how to name polyatomic compounds, read on!

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    Article Info


    Categories: Chemical Nomenclature

    In other languages:

    Español: nombrar compuestos químicos, Português: Nomear Compostos Químicos, Deutsch: Bezeichnung von chemischen Verbindungen, Italiano: Attribuire un Nome ai Composti Chimici, Русский: называть химические соединения, 中文: 给化合物命名, Français: nommer les composés chimiques, Bahasa Indonesia: Memberi Nama Senyawa Kimia, Nederlands: Chemische bindingen benoemen

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