Systematic name

These can be as simple as assigning a prefix and a number to each object (in which case they are a sort of catalog reference), or as complex as encoding the complete structure of the object in the name. Many systems combine some information about the named object with an extra sequence number to make it into a unique identifier.

• Systematic names for chemical elements and chemical compounds (administered by the IUPAC)
• Systematic names for biological organisms, initiated by Carolus Linnaeus: see scientific classification and binomial name
• Systematic names for asteroids, comets, stars and other astronomical objects (administered by the International Astronomical Union)
• Systematic names for genes, proteins, and other objects of molecular biology

Chemical Names

To give an example of why this is so, consider this example. The names "caffeine" and "3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione" both describe the same chemical.
The systematic name encodes the structure and composition of the caffiene molecule in some detail, and provides an unambiguous reference to this compound, whereas the name "caffeine" just names it. These advantages make the systematic name far superior to the common name when absolute clarity and precision is required. However, even professional chemists will use the non-systematic name 99% of the time, because caffeine is a well-known common chemical with a unique structure. Similarly, the chemical water is always known as such, never as "dihydrogen monoxide."

1. Single atom anions are named with an -ide suffix, for example H^- is hydride.

2. 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.

3. Cations able to take on more than one positive charge are labeled with Roman numerals in parentheses. For example, Cu⁺ is copper(I), Cu²⁺ is copper(II). An older, depreciated 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).

4. Oxyanions (polyatomic anions containing oxygen) are named with -ite or -ate, for a lesser or greater quantity of oxygen. For example, NO₂^- is nitrite, while NO₃^- is nitrate. If four oxyanions are possible, the prefixes hypo- and per- are used: Hypochlorite is ClO^-, Perchlorate is ClO₄^-,

5. The prefix bi- is a depreciated 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".

Naming Simple Ionic Compounds

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], for more details see selected pages from IUPAC rules for naming inorganic compounds.

Naming Hydrates