-ium

A systematic element name is the temporary name assigned to an unknown or recently synthesized chemical element. A systematic symbol is also derived from this name.

In chemistry, a transuranic element receives a permanent name and symbol only after its synthesis has been confirmed. In some cases, such as the Transfermium Wars, controversies over the formal name and symbol have been protracted and highly political. In order to discuss such elements without ambiguity, the International Union of Pure and Applied Chemistry (IUPAC) uses a set of rules, adopted in 1978, to assign a temporary systematic name and symbol to each such element. This approach to naming originated in the successful development of regular rules for the naming of organic compounds.

IUPAC rules[]

The temporary names derive systematically from the element's atomic number, and apply only to 101 ≤ Z ≤ 999.[1] Each digit is translated into a "numerical root" according to the table. The roots are concatenated, and the name is completed by the suffix -ium. Some of the roots are Latin and others are Greek, to avoid two digits starting with the same letter (for example, the Greek-derived pent is used instead of the Latin-derived quint to avoid confusion with quad for 4). There are two elision rules designed to prevent odd-looking names.

Digit Root Etymology Symbol Pronunciation
0 nil Latin nihil ("nothing") n /nɪl/
1 un Latin unus ("one") u /n/
2 bi Latin bis ("twice") b /b/
3 tri Latin tres ("three")
Greek tria ("three")
t /tr/
4 quad Latin quattuor ("four") q /kwɒd/
5 pent Greek pente ("five") p /pɛnt/
6 hex Greek hex ("six") h /hɛks/
7 sept Latin septem ("seven") s /sɛpt/
8 oct Latin octo ("eight")
Greek okto ("eight")
o /ɒkt/
9 en(n) Greek ennea ("nine") e /ɛn/
Suffix -(i)um Latin -um (neuter singular) none /-iəm/

If bi or tri is followed by the ending -ium (i.e. the last digit is 2 or 3), the result is -bium or -trium, not *-biium or *-triium.

Example 1: element 122: unbibium (Ubb)
Example 2: element 123: unbitrium (Ubt)

If enn is followed by nil (i.e. the sequence -90- occurs), the result is -ennil-, not *-ennnil-.

Example 3: element 190: unennilium (Uen)

The suffix -ium overrides traditional chemical-suffix rules; thus, elements 117 and 118 were ununseptium and ununoctium, not *ununseptine and *ununocton.[2] This does not apply to the trivial names these elements receive once confirmed; thus, elements 117 and 118 are now tennessine and oganesson, respectively. For these trivial names, all elements receive the suffix -ium except those in group 17, which receive -ine (like the halogens), and those in group 18, which receive -on (like the noble gases).

The systematic symbol is formed by taking the first letter of each root, converting the first to a capital. This results in three-letter symbols instead of the one- or two-letter symbols used for named elements. The rationale is that any scheme producing two-letter symbols will have to deviate from full systematicity to avoid collisions with the symbols of the permanently named elements.

The Recommendations for the Naming of Elements of Atomic Numbers Greater than 100 can be found here.

As of 2019, all 118 discovered elements have received individual permanent names and symbols.[3] Therefore, systematic names and symbols are now used only for the undiscovered elements beyond element 118, oganesson. When such an element is discovered, it will keep its systematic name and symbol until its discovery meets the criteria of and is accepted by the IUPAC/IUPAP Joint Working Party, upon which the discoverers are invited to propose a permanent name and symbol. Once this name and symbol is proposed, there is still a comment period before they become official and replace the systematic name and symbol.

At the time the systematic names were recommended (1978), names had already been officially given to all elements up to atomic number 103, lawrencium. While systematic names were given for elements 101 (mendelevium), 102 (nobelium), and 103 (lawrencium), these were only as "minor alternatives to the trivial names already approved by IUPAC".[1] The following elements for some time only had systematic names as approved names, until their final replacement with trivial names after their discoveries were accepted.

Z Systematic Trivial Year
Symbol Name Symbol Name Undisputed synthesis 1st published Named
104 Unq Unnilquadium Rf Rutherfordium 1969 1997
105 Unp Unnilpentium Db Dubnium 1970 1997
106 Unh Unnilhexium Sg Seaborgium 1974 1997
107 Uns Unnilseptium Bh Bohrium 1981 1997
108 Uno Unniloctium Hs Hassium 1984 1997
109 Une Unnilennium Mt Meitnerium 1982 1997
110 Uun Ununnilium Ds Darmstadtium 1995 2003
111 Uuu Unununium Rg Roentgenium 1995 2004
112 Uub Ununbium Cn Copernicium 1996 2010
113 Uut Ununtrium Nh Nihonium 2004 2016
114 Uuq Ununquadium Fl Flerovium 1999 2012
115 Uup Ununpentium Mc Moscovium 2004 2016
116 Uuh Ununhexium Lv Livermorium 2000 2012
117 Uus Ununseptium Ts Tennessine 2010 2016
118 Uuo Ununoctium Og Oganesson 2006 2016

References[]

  1. ^ a b https://www.qmul.ac.uk/sbcs/iupac/AtWt/element.html
  2. ^ Koppenol, W. (2016). "How to name new chemical elements" (PDF). Pure and Applied Chemistry. DeGruyter. doi:10.1515/pac-2015-0802. hdl:10045/55935. S2CID 102245448.
  3. ^ "IUPAC Announces the Names of the Elements 113, 115, 117, and 118". IUPAC. 2016-11-30. Retrieved 2016-11-30.

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