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IUPAC Nomenclature of Elements with Z > 100

The systematic approach to naming superheavy elements before their official discovery.

By chemca Team • Updated Jan 2026

The discovery of elements with atomic numbers greater than 100 often leads to competition between laboratories worldwide. To avoid confusion and disputes before an official name is ratified, the IUPAC (International Union of Pure and Applied Chemistry) established a systematic nomenclature based on Latin and Greek numerical roots.

1. Numerical Roots

The name of the element is derived directly from the digits of its atomic number using the following roots:

Digit	Name	Abbreviation
0	nil	n
1	un	u
2	bi	b
3	tri	t
4	quad	q
5	pent	p
6	hex	h
7	sept	s
8	oct	o
9	enn	e

2. Rules for Naming

1. Identify Digits: Break the atomic number into its digits. Example: $104 \rightarrow 1, 0, 4$.
2. Combine Roots: Write the roots for the digits in order. Example: $un + nil + quad$.
3. Add Suffix: Append -ium to the end. Example: $un + nil + quad + ium$.
4. Symbol Generation: The three-letter symbol is formed from the first letter of each root. Example: $Unq$.

Important Exceptions (to avoid bad phonetics):

• bi + ium: If the root ends in 'i' (bi) and the suffix is 'ium', do not double the 'i'.
  Correct: Bium. Incorrect: Biium.
• tri + ium: Same as above.
  Correct: Trium. Incorrect: Triium.
• enn + nil: If 'enn' (9) occurs before 'nil' (0), the final 'n' of 'enn' is dropped.
  Correct: Ennil. Incorrect: Ennnil.

3. Examples

Atomic Number (Z)	Roots	Systematic Name	Symbol	Official IUPAC Name
101	1(un) + 0(nil) + 1(un)	Unnilunium	Unu	Mendelevium (Md)
104	1(un) + 0(nil) + 4(quad)	Unnilquadium	Unq	Rutherfordium (Rf)
111	1(un) + 1(un) + 1(un)	Unununium	Uuu	Roentgenium (Rg)
118	1(un) + 1(un) + 8(oct)	Ununoctium	Uuo	Oganesson (Og)
120 (Hypothetical)	1(un) + 2(bi) + 0(nil)	Unbinilium	Ubn	-

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