Nomenclature of Elements with Atomic Number > 100

Elements with Atomic Number > 100 (IUPAC)

Where a newly discovered chemical element has an atomic number greater than 100 and an official name has not yet been adopted, the IUPAC system provides a systematic temporary name and a three-letter temporary symbol. These systematic names are derived from the decimal digits of the atomic number by using specific roots for each digit and ending the name with the suffix -ium. The temporary three-letter symbol is formed from the first letter of each digit-root, with the first letter capitalised and the remaining letters lower-case (for example, Uuo for ununoctium).

Rules for forming the systematic temporary name

• Write the decimal digits of the atomic number in order; replace each digit by its corresponding root (from the table above).
• Join the roots together in the same order as the digits, then add the suffix -ium to form the systematic name (for example, atomic number 118 → 1-1-8 → un-un-oct + -ium = ununoctium).
• The temporary symbol is formed from the first letter of each root (for example, ununoctium → Uuo).
• If necessary to avoid awkward or incorrect vowel sequences, small orthographic adjustments are made when joining roots (for practical usage some vowels may be omitted or contracted), but the basic method is concatenation of the digit-roots followed by -ium.
• These systematic names and symbols are provisional; they are used only until an official name and symbol, approved by IUPAC, are assigned.

Notation for IUPAC nomenclature of higher elements

Nomenclature of specific elements (Z = 104 to 118)

The table below lists the IUPAC systematic (temporary) names and three-letter temporary symbols historically used for elements with atomic numbers 104-118, together with their currently accepted official IUPAC names and symbols (where assigned).

Worked examples of forming systematic names and symbols

Example - atomic number 118:

• Digits: 1, 1, 8 → roots: un, un, oct
• Join and add suffix: un + un + oct + -ium = ununoctium
• Temporary symbol: first letters of roots → Uuo
• Official name and symbol (IUPAC): Oganesson, Og

Example - atomic number 115:

• Digits: 1, 1, 5 → roots: un, un, pent
• Join and add suffix: ununpentium
• Temporary symbol: Uup
• Official name and symbol (IUPAC): Moscovium, Mc

Practical notes and IUPAC policy

• The temporary systematic names and symbols were introduced so scientists could refer unambiguously to newly reported elements before a formal name was agreed by IUPAC.
• Once an element's discovery is confirmed and a name proposal is accepted, IUPAC publishes the official name and symbol; these replace the temporary systematic versions.
• Official names often honour a scientist, a place, a laboratory or have other justified origins (for example, Seaborgium for Glenn Seaborg, Darmstadtium for Darmstadt, Copernicium for Copernicus).
• For writing symbols correctly: official element symbols always have the first letter capitalised and the second letter (if any) lower-case; temporary three-letter symbols follow the same capitalization rule.
• Textbooks and examinations generally require knowledge of both the systematic temporary names (for historical or conceptual understanding) and the currently accepted official names and symbols.

Summary

The IUPAC systematic naming scheme for elements with atomic number greater than 100 uses roots for digits 0-9 joined in order and the suffix -ium, producing a provisional name and a three-letter provisional symbol. These provisional names are used until IUPAC formally accepts an official name and symbol. For practical study, memorise the digit roots and the official names and symbols of known elements up to 118.