Chemical Name Calculator

Enter a chemical formula to find its IUPAC name, common name, molar mass, and bond type, or build a compound from ions to see the correct formula and systematic name instantly.

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Type any chemical formula such as H2O, NaOH, KMnO4, C6H12O6, etc.

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Common Name

Bond Type

Molar Mass

Component Ions

What Is Chemical Nomenclature?

Chemical nomenclature is the systematic method used to name chemical compounds according to a set of internationally recognized rules established by the International Union of Pure and Applied Chemistry (IUPAC). These rules ensure that every chemical substance has a unique and unambiguous name that conveys information about its composition and, in many cases, its structure. Before standardized naming conventions existed, chemists used common or trivial names that varied by region and language, leading to confusion. For example, "muriatic acid" and "spirits of salt" both refer to hydrochloric acid (HCl), while "quicklime" is simply calcium oxide (CaO). IUPAC nomenclature replaced this patchwork system with a rational, consistent framework that scientists around the world can understand immediately.

The importance of chemical nomenclature cannot be overstated. In research laboratories, pharmaceutical companies, regulatory agencies, and educational institutions, the ability to communicate the exact identity of a substance is critical for safety, reproducibility, and legal compliance. A misnamed chemical can lead to dangerous reactions, failed experiments, or regulatory violations. This calculator helps you bridge the gap between a chemical formula and its proper systematic name by providing the IUPAC name, common name (where applicable), molar mass, bond type, and component ions for over 100 common compounds.

Atoms vs. Ions

An atom is the smallest unit of an element that retains the chemical identity of that element. Every atom consists of a nucleus containing protons (positively charged) and neutrons (neutral), surrounded by a cloud of electrons (negatively charged). In a neutral atom, the number of protons equals the number of electrons, so there is no net electrical charge. For instance, a neutral sodium atom (Na) has 11 protons and 11 electrons.

An ion is an atom or group of atoms that has gained or lost one or more electrons, giving it a net positive or negative charge. When a neutral atom loses electrons, it becomes a positively charged ion called a cation. When it gains electrons, it becomes a negatively charged ion called an anion. Ions form because certain electron configurations are more energetically stable than others. Metals tend to lose electrons to achieve a noble gas configuration, while nonmetals tend to gain electrons for the same reason.

The distinction between atoms and ions is fundamental to understanding chemical bonding. In metallic elements, atoms share electrons in a "sea" of delocalized electrons. In ionic compounds, cations and anions are held together by electrostatic attraction. In covalent compounds, atoms share electron pairs. Understanding whether you are dealing with atoms or ions determines which naming rules you will apply.

Cations and Anions

Cations (Positive Ions)

Cations are formed when atoms lose electrons. The name of a monatomic cation is simply the name of the element followed by the word "ion." For example, Na⁺ is the sodium ion, and Ca²⁺ is the calcium ion. Many transition metals can form cations with different charges. Iron, for instance, can form Fe²⁺ (iron(II) or ferrous ion) and Fe³⁺ (iron(III) or ferric ion). In modern IUPAC nomenclature, Roman numerals in parentheses indicate the charge of the metal ion, which is called the Stock notation. This system is preferred over the older -ous/-ic suffixes because it is unambiguous.

The polyatomic cation NH₄⁺ (ammonium) is one of the most important cations in chemistry. It is formed when ammonia (NH₃) accepts a proton (H⁺). Ammonium salts such as ammonium chloride (NH₄Cl) and ammonium nitrate (NH₄NO₃) are widely used in fertilizers, cleaning products, and explosives.

Anions (Negative Ions)

Anions are formed when atoms gain electrons. Monatomic anions are named by changing the ending of the element name to "-ide." For example, Cl^- is the chloride ion, O^2- is the oxide ion, and S^2- is the sulfide ion. Polyatomic anions are groups of covalently bonded atoms that carry a net negative charge. Common examples include sulfate (SO₄^2-), nitrate (NO₃^-), carbonate (CO₃^2-), and phosphate (PO₄^3-).

Many polyatomic anions come in pairs that differ by one oxygen atom. The one with more oxygen atoms typically gets the "-ate" suffix, while the one with fewer oxygen atoms gets the "-ite" suffix. For example, SO₄^2- is sulfate and SO₃^2- is sulfite; NO₃^- is nitrate and NO₂^- is nitrite. When there are more than two oxyanions in a series, the prefixes "per-" (more oxygen than -ate) and "hypo-" (fewer oxygen than -ite) are used. The chlorine oxyanion series illustrates this well: ClO₄^- (perchlorate), ClO₃^- (chlorate), ClO₂^- (chlorite), and ClO^- (hypochlorite).

Ionic vs. Covalent Compounds

Chemical compounds fall into two broad categories based on the type of bonding between their constituent atoms: ionic compounds and covalent (molecular) compounds. Understanding the difference is essential for correct naming.

Ionic compounds form when one or more electrons are transferred from a metal atom to a nonmetal atom, creating oppositely charged ions that attract each other. These compounds typically consist of a metal cation and a nonmetal anion (or polyatomic ion). They tend to have high melting and boiling points, conduct electricity when dissolved in water or melted, and form crystalline structures. Examples include sodium chloride (NaCl), calcium carbonate (CaCO₃), and iron(III) oxide (Fe₂O₃).

Covalent compounds (also called molecular compounds) form when two nonmetal atoms share electron pairs. These compounds tend to have lower melting and boiling points, do not conduct electricity in solution, and can exist as gases, liquids, or soft solids at room temperature. Examples include water (H₂O), carbon dioxide (CO₂), and methane (CH₄). The naming rules for covalent compounds differ significantly from those for ionic compounds.

A useful rule of thumb: if a compound contains a metal (or NH₄⁺) combined with a nonmetal or polyatomic anion, it is likely ionic. If it contains only nonmetals (excluding NH₄⁺ salts), it is likely covalent. However, some compounds have characteristics of both types. For instance, aluminum chloride (AlCl₃) is often considered ionic but exhibits significant covalent character.

Naming Ionic Compounds

Binary Ionic Compounds

A binary ionic compound contains exactly two elements: a metal and a nonmetal. To name a binary ionic compound, write the name of the cation (the metal) first, followed by the name of the anion with its ending changed to "-ide." For example, NaCl is sodium chloride, MgO is magnesium oxide, and CaBr₂ is calcium bromide. The formula reflects the ratio of ions needed to achieve electrical neutrality. Since Na is +1 and Cl is -1, they combine in a 1:1 ratio. Since Ca is +2 and Br is -1, two bromide ions are needed for every calcium ion.

Transition Metals and Roman Numerals (Stock Notation)

Many transition metals can form cations with different charges. When naming compounds of these metals, you must indicate the charge of the metal ion using Roman numerals in parentheses after the metal name. For example, FeCl₂ contains Fe²⁺ and is named iron(II) chloride, while FeCl₃ contains Fe³⁺ and is named iron(III) chloride. Similarly, CuO is copper(II) oxide (Cu²⁺) and Cu₂O is copper(I) oxide (Cu⁺). This convention eliminates ambiguity. Metals that have only one common charge (such as Na⁺, K⁺, Ca²⁺, Al³⁺) do not require Roman numerals.

Compounds with Polyatomic Ions

When an ionic compound contains a polyatomic ion, the naming follows the same pattern: name the cation first, then the anion. The polyatomic ion keeps its own name. For example, NaNO₃ is sodium nitrate, CaCO₃ is calcium carbonate, K₂SO₄ is potassium sulfate, and Fe₂(SO₄)₃ is iron(III) sulfate. Note that in the formula, parentheses are used around the polyatomic ion when more than one is needed, with the subscript outside the parentheses indicating how many of that ion are present.

Naming Covalent (Molecular) Compounds

Covalent compounds consisting of two nonmetals are named using Greek prefixes to indicate the number of each type of atom in the molecule. The prefixes are:

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

The first element in the formula is named with its prefix (except "mono-" is usually dropped for the first element), and the second element is named with a prefix and the "-ide" suffix. For example, CO₂ is carbon dioxide (not monocarbon dioxide), N₂O₄ is dinitrogen tetroxide, PCl₅ is phosphorus pentachloride, and SF₆ is sulfur hexafluoride. When a prefix ends in "a" or "o" and the element name begins with "a" or "o," the final vowel of the prefix is often dropped for easier pronunciation (e.g., "monoxide" rather than "monooxide").

Naming Acids

Acids are a special category of compounds that produce hydrogen ions (H⁺) when dissolved in water. Their names depend on whether the anion contains oxygen.

Binary Acids (No Oxygen)

If the acid is formed from hydrogen and a single nonmetal element (with no oxygen), it is named with the prefix "hydro-" followed by the root of the nonmetal name and the suffix "-ic acid." For example, HCl is hydrochloric acid, HBr is hydrobromic acid, HF is hydrofluoric acid, and H₂S is hydrosulfuric acid.

Oxyacids (Contain Oxygen)

If the acid contains a polyatomic anion with oxygen, the name is derived from the anion name. If the anion ends in "-ate," the acid name uses the suffix "-ic acid." If the anion ends in "-ite," the acid name uses the suffix "-ous acid." For example, H₂SO₄ contains the sulfate ion (SO₄^2-) and is called sulfuric acid. H₂SO₃ contains the sulfite ion (SO₃^2-) and is called sulfurous acid. HNO₃ contains the nitrate ion (NO₃^-) and is called nitric acid. HNO₂ contains the nitrite ion (NO₂^-) and is called nitrous acid. HClO₄ is perchloric acid, HClO₃ is chloric acid, HClO₂ is chlorous acid, and HClO is hypochlorous acid.

Common Polyatomic Ions

The following table lists the most important polyatomic ions that every chemistry student should memorize. Knowing these ions is essential for correctly naming and writing formulas for a vast number of compounds.

Ion Formula	Name	Charge
NH₄⁺	Ammonium	1+
OH^-	Hydroxide	1-
NO₃^-	Nitrate	1-
NO₂^-	Nitrite	1-
SO₄^2-	Sulfate	2-
SO₃^2-	Sulfite	2-
CO₃^2-	Carbonate	2-
HCO₃^-	Hydrogen carbonate (Bicarbonate)	1-
PO₄^3-	Phosphate	3-
HPO₄^2-	Hydrogen phosphate	2-
H₂PO₄^-	Dihydrogen phosphate	1-
ClO₄^-	Perchlorate	1-
ClO₃^-	Chlorate	1-
ClO₂^-	Chlorite	1-
ClO^-	Hypochlorite	1-
CH₃COO^-	Acetate	1-
C₂O₄^2-	Oxalate	2-
MnO₄^-	Permanganate	1-
CrO₄^2-	Chromate	2-
Cr₂O₇^2-	Dichromate	2-
CN^-	Cyanide	1-
SCN^-	Thiocyanate	1-
S₂O₃^2-	Thiosulfate	2-
BrO₃^-	Bromate	1-
IO₃^-	Iodate	1-
SiO₃^2-	Silicate	2-

Examples of Chemical Naming

Let us work through several examples to solidify your understanding of chemical nomenclature:

NaCl -- Sodium is a metal cation (Na⁺) and chlorine becomes the chloride anion (Cl^-). Since sodium has only one common charge, no Roman numeral is needed. The name is sodium chloride.
Fe₂O₃ -- Iron is a transition metal that can have multiple charges. Since there are 2 Fe and 3 O^2- (total charge of 6-), each Fe must be 3+. The name is iron(III) oxide.
CaCO₃ -- Calcium (Ca²⁺) combined with the polyatomic carbonate ion (CO₃^2-). The name is calcium carbonate.
H₂SO₄ -- This is an acid containing the sulfate ion. Sulfate ends in "-ate," so the acid ends in "-ic acid." The name is sulfuric acid.
N₂O₅ -- Two nonmetals, so we use Greek prefixes. The name is dinitrogen pentoxide.
CO -- A covalent compound of carbon and oxygen. With one carbon and one oxygen, the name is carbon monoxide (the "mono-" prefix is used for the second element but dropped for the first).
KMnO₄ -- Potassium (K⁺) combined with the permanganate ion (MnO₄^-). The name is potassium permanganate.
Cu₂O -- Copper is a transition metal. With 2 Cu and 1 O^2- (charge 2-), each Cu must be 1+. The name is copper(I) oxide.
Al₂(SO₄)₃ -- Aluminum (Al³⁺) combined with sulfate (SO₄^2-). Two Al³⁺ give 6+ and three SO₄^2- give 6-, balancing the compound. The name is aluminum sulfate.
HNO₃ -- An oxyacid containing the nitrate ion. Nitrate ends in "-ate," so the acid ends in "-ic acid." The name is nitric acid.

How to Use This Calculator

This Chemical Name Calculator offers two convenient modes to help you identify and name chemical compounds:

Mode 1: Formula to Name

Simply type any chemical formula into the input box. The formula should use standard chemical notation, where element symbols start with a capital letter optionally followed by a lowercase letter, and subscript numbers indicate the count of each atom. For example, type "NaCl" for sodium chloride, "H2SO4" for sulfuric acid, or "Ca(OH)2" for calcium hydroxide. Then click the "Find Name" button. The calculator will search its comprehensive database of over 100 compounds and display the IUPAC name, common name (if one exists), bond type (ionic or covalent), molar mass in grams per mole, and component ions for ionic compounds.

Mode 2: Build from Ions

If you are working on an ionic compound and want to see how two ions combine, switch to the "Build from Ions" tab. Select a cation from the first dropdown and an anion from the second dropdown. The calculator will automatically determine the correct ratio of ions to balance the charges, generate the formula, and look up the compound name. This mode is particularly useful for students learning to write ionic formulas and for quickly checking your work on homework or lab reports.

Both modes calculate the molar mass by summing the atomic masses of all atoms in the formula. The molar mass is given in grams per mole (g/mol), rounded to two decimal places. For ionic compounds, the component ions are listed so you can verify the cation and anion that make up the substance. For covalent compounds, the bond type is listed as "Covalent" and the component ions field will display "N/A (Molecular compound)."

Frequently Asked Questions (FAQ)

Q: What is the difference between IUPAC names and common names?

A: IUPAC names are systematic names assigned according to rules established by the International Union of Pure and Applied Chemistry. They are designed to be unambiguous and universally understood by chemists worldwide. Common names, on the other hand, are traditional or colloquial names that have been used historically. For example, NaCl has the IUPAC name "sodium chloride" and the common names "table salt" or "halite." H₂O has the IUPAC name "dihydrogen monoxide" but is universally known by its common name "water." While IUPAC names are the standard in scientific literature, common names remain widely used in everyday language and industry.

Q: Why do some elements require Roman numerals in their compound names?

A: Roman numerals are required when a metal can form cations with more than one possible charge, which is common among transition metals. For example, iron can be Fe²⁺ or Fe³⁺, copper can be Cu⁺ or Cu²⁺, and tin can be Sn²⁺ or Sn⁴⁺. The Roman numeral, placed in parentheses after the metal name, tells you the exact charge. FeCl₂ is iron(II) chloride and FeCl₃ is iron(III) chloride -- two different compounds with different properties. Metals with only one common oxidation state (such as sodium, potassium, calcium, and aluminum) do not need Roman numerals because there is no ambiguity.

Q: How do I know if a compound is ionic or covalent?

A: A general rule is that compounds formed between metals and nonmetals (or polyatomic ions) are ionic, while compounds formed between two or more nonmetals are covalent. You can look at the periodic table to determine this: elements on the left side and in the middle (metals) combined with elements on the right side (nonmetals) form ionic compounds. Two elements from the right side of the periodic table form covalent compounds. Notable exceptions include ammonium (NH₄⁺) salts, which are ionic even though nitrogen and hydrogen are nonmetals, and some metallic compounds like AlCl₃ that exhibit significant covalent character.

Q: What is molar mass and why is it important?

A: Molar mass is the mass of one mole of a substance, expressed in grams per mole (g/mol). One mole contains approximately 6.022 x 10²³ particles (Avogadro's number). Molar mass is calculated by summing the atomic masses of all atoms in the formula. For example, H₂O has a molar mass of approximately 18.02 g/mol (2 x 1.008 for hydrogen + 1 x 16.00 for oxygen). Molar mass is essential for converting between grams and moles in stoichiometric calculations, preparing solutions of specific concentrations, and determining the amounts of reactants and products in chemical reactions.

Q: Can this calculator name organic compounds?

A: This calculator includes some common organic compounds in its database, such as methane (CH₄), ethanol (C₂H₅OH), acetic acid (CH₃COOH), glucose (C₆H₁₂O₆), and others. However, organic nomenclature is a vast and complex system with its own set of IUPAC rules involving parent chains, substituents, functional groups, and stereochemistry. A comprehensive organic naming tool would require a separate, specialized calculator. This tool focuses primarily on inorganic compounds, acids, and common small organic molecules.

Q: What does the subscript number in a chemical formula mean?

A: A subscript number in a chemical formula indicates how many atoms of the preceding element are present in one formula unit or molecule of the compound. For example, in H₂O, the subscript 2 after H means there are two hydrogen atoms for every one oxygen atom. In Ca(OH)₂, the subscript 2 outside the parentheses means there are two hydroxide (OH) groups, giving a total of two oxygen atoms and two hydrogen atoms along with one calcium atom. When no subscript is written, it is understood to be 1. Subscripts are crucial for determining the molar mass and for balancing chemical equations.

Q: How do I write the formula of an ionic compound from ion charges?

A: To write the formula of an ionic compound, you need the charges of the cation and anion. The overall compound must be electrically neutral. Use the "crisscross method": take the magnitude of each ion's charge and use it as the subscript for the other ion. Then simplify if possible. For example, to write the formula for aluminum oxide: Al is 3+ and O is 2-. Crisscrossing gives Al₂O₃. For calcium chloride: Ca is 2+ and Cl is 1-. Crisscrossing gives CaCl₂. For iron(III) sulfate: Fe is 3+ and SO₄ is 2-. Crisscrossing gives Fe₂(SO₄)₃. This calculator's "Build from Ions" mode performs this process automatically.

Q: Why do some acids have "hydro-" in their name and others do not?

A: The prefix "hydro-" is used only for binary acids, which are acids composed of hydrogen and one other element with no oxygen. For example, HCl is hydrochloric acid and HBr is hydrobromic acid. Oxyacids, which contain hydrogen, oxygen, and another element, do not use the "hydro-" prefix. Instead, their names are derived from the polyatomic anion: if the anion name ends in "-ate," the acid name ends in "-ic acid" (e.g., sulfate becomes sulfuric acid); if the anion name ends in "-ite," the acid name ends in "-ous acid" (e.g., sulfite becomes sulfurous acid). This naming convention helps distinguish between these two fundamentally different types of acids.