chemistry

IUPAC nomenclature of inorganic chemistry

IUPAC nomenclature of inorganic chemistry is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand IUPAC nomenclature of inorganic chemistry rather than just read about it. In short: In chemical nomenclature, the IUPAC nomenclature of inorganic chemistry is a systematic method of naming inorganic chemical compounds, as recommended by the International Union of Pure and Applied Chemistry (IUPAC). It is published in Nomenclature of Inorganic Chemistry (which is informally called the Red Book).

Key takeaways

IUPAC nomenclature of inorganic chemistry belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect IUPAC nomenclature of inorganic chemistry to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of IUPAC nomenclature of inorganic chemistry from memory before moving on to harder problems.

Reference excerpt

In chemical nomenclature, the IUPAC nomenclature of inorganic chemistry is a systematic method of naming inorganic chemical compounds, as recommended by the International Union of Pure and Applied Chemistry (IUPAC). It is published in Nomenclature of Inorganic Chemistry (which is informally called the Red Book). Ideally, every inorganic compound should have a name from which an unambiguous formula can be determined. There is also an IUPAC nomenclature of organic chemistry.

System The names "caffeine" and "3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione" both signify the same chemical compound. The systematic name encodes the structure and composition of the caffeine molecule in some detail, and provides an unambiguous reference to this compound, whereas the name "caffeine" simply names it. These advantages make the systematic name far superior to the common name when absolute clarity and precision are required. However, for the sake of brevity, even professional chemists will use the non-systematic name almost all of the time, because caffeine is a well-known common chemical with a unique structure. Similarly, H2O is most often simply called water in English, though other chemical names do exist.

Single atom anions are named with an -ide suffix: for example, F− is fluoride. Compounds with a positive ion (cation): The name of the compound is simply the cation's name (usually the same as the element's), followed by the anion. For example, NaCl is sodium chloride, and CaF2 is calcium fluoride. Cations of transition metals able to take multiple charges are labeled with Roman numerals in parentheses to indicate their charge. For example, Cu+ is copper(I), Cu2+ is copper(II). An older, deprecated notation is to append -ous or -ic to the root of the Latin name to name ions with a lesser or greater charge. Under this naming convention, Cu+ is cuprous and Cu2+ is cupric. For naming metal complexes see the page on complex (chemistry). Oxyanions (polyatomic anions containing oxygen) are named with -ite or -ate, for a lesser or greater quantity of oxygen, respectively. For example, NO−2 is nitrite, while NO−3 is nitrate. If four oxyanions are possible, the prefixes hypo- and per- are used: hypochlorite is ClO−, perchlorate is ClO−4. The prefix bi- is a deprecated way of indicating the presence of a single hydrogen ion, as in "sodium bicarbonate" (NaHCO3). The modern method specifically names the hydrogen atom. Thus, NaHCO3 would be pronounced sodium hydrogen carbonate. Positively charged ions are called cations and negatively charged ions are called anions. The cation is always named first. Ions can be metals, non-metals or polyatomic ions. Therefore, the name of the metal or positive polyatomic ion is followed by the name of the non-metal or negative polyatomic ion. The positive ion retains its element name whereas for a single non-metal anion the ending is changed to -ide.

Example: sodium chloride, potassium oxide, or calcium carbonate. When the metal has more than one possible ionic charge or oxidation number the name becomes ambiguous. In these cases the oxidation number (the same as the charge) of the metal ion is represented by a Roman numeral in parentheses immediately following the metal ion name. For example, in uranium(VI) fluoride the oxidation number of uranium is 6. Another example is the iron oxides. FeO is iron(II) oxide and Fe2O3 is iron(III) oxide. An older system used prefixes and suffixes to indicate the oxidation number, according to the following scheme:

Thus the four oxyacids of chlorine are called hypochlorous acid (HOCl), chlorous acid (HOClO), chloric acid (HOClO2) and perchloric acid (HOClO3), and their respective conjugate bases are hypochlorite, chlorite, chlorate and perchlorate ions. This system has partially fallen out of use, but survives in the common names of many chemical compounds: the modern literature contains few references to "ferric chloride" (instead calling it "iron(III) chloride"), but names like "potassium permanganate" (instead of "potassium manganate(VII)") and "sulfuric acid" abound.

Traditional naming

Simple ionic compounds An ionic compound is named by its cation followed by its anion. See polyatomic ion for a list of possible ions. For cations that take on multiple charges, the charge is written using Roman numerals in parentheses immediately following the element name. For example, Cu(NO3)2 is copper(II) nitrate, because the charge of two nitrate ions (NO−3) is 2 × −1 = −2, and since the net charge of the ionic compound must be zero, the Cu ion has a 2+ charge. This compound is therefore copper(II) nitrate. In the case of cations with a +4 oxidation state, the only acceptable format for the Roman numeral 4 is IV and not IIII. The Roman numerals in fact show the oxidation number, but in simple ionic compounds (i.e., not metal complexes) this will always equal the ionic charge on the metal. For a simple overview see [1] Archived 2008-10-16 at the Wayback Machine, for more details see selected pages from IUPAC rules for naming inorganic compounds Archived 2016-03-03 at the Wayback Machine.

List of common ion names Monatomic anions:

Cl− chloride S2− sulfide P3− phosphide Polyatomic ions:

NH+4 ammonium H3O+ hydronium NO−3 nitrate NO−2 nitrite ClO− hypochlorite ClO−2 chlorite ClO−3 chlorate ClO−4 perchlorate SO2−3 sulfite SO2−4 sulfate S2O2–3 thiosulfate HSO−3 hydrogen sulfite (or bisulfite) HCO−3 hydrogen carbonate (or bicarbonate) CO2−3 carbonate PO3−4 phosphate HPO2−4 hydrogen phosphate H2PO−4 dihydrogen phosphate CrO2−4 chromate Cr2O2−7 dichromate BO3−3 borate AsO3−4 arsenate C2O2−4 oxalate CN− cyanide SCN− thiocyanate MnO−4 permanganate

Hydrates Hydrates are ionic compounds that have absorbed water. They are named as the ionic compound followed by a numerical prefix and -hydrate. The numerical prefixes used are listed below (see IUPAC numerical multiplier):

mono- di- tri- tetra- penta- hexa- hepta- octa- nona- deca- For example, CuSO4·5H2O is "copper(II) sulfate pentahydrate".

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with IUPAC nomenclature of inorganic chemistry

Start with the simplest possible case. Write down what IUPAC nomenclature of inorganic chemistry claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to IUPAC nomenclature of inorganic chemistry before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about IUPAC nomenclature of inorganic chemistry ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of IUPAC nomenclature of inorganic chemistry

In research: IUPAC nomenclature of inorganic chemistry appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses IUPAC nomenclature of inorganic chemistry in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: IUPAC nomenclature of inorganic chemistry is common in secondary-school and first-year university syllabi. It links to neighbouring topics Chemical nomenclature, Chemistry reference works, Inorganic chemistry, so understanding it makes those chapters shorter.
In everyday life: Look for IUPAC nomenclature of inorganic chemistry outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study IUPAC nomenclature of inorganic chemistry in 20 minutes

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Close the page and write down what IUPAC nomenclature of inorganic chemistry means in your own words.
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Frequently asked questions

What is IUPAC nomenclature of inorganic chemistry in simple terms?

Why does IUPAC nomenclature of inorganic chemistry matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study IUPAC nomenclature of inorganic chemistry?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on IUPAC nomenclature of inorganic chemistry.