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Exam papers often ask for the IUPAC name and symbol of an element such as 119 or 120, and students often lose the mark on a spelling rule. The method is mechanical: ten digit roots, one ending and two spelling rules. This post sets out the rules from the original IUPAC recommendation, works through examples that test each rule, and explains how temporary names become permanent ones.
Where is this in the syllabus?
The NCERT Class 11 chapter Classification of Elements and Periodicity in Properties, section 3.4, explains the system and gives the roots in Table 3.4 and the names for elements 101 to 118 in Table 3.5. Its Problem 3.1 asks for the name of element 120. The JEE (Main) 2026 syllabus and NEET (UG) 2026 syllabus include "Classification of elements and periodicity in properties" and the present form of the periodic table. Check the syllabus for your exam year.
Why does IUPAC use temporary names at all?
NCERT tells the story of element 104: American scientists named it rutherfordium and Soviet scientists named it kurchatovium, each claiming the discovery. To avoid such clashes, IUPAC's 1979 recommendations give every element above 100 a systematic name derived from its atomic number. The names had to be short, clearly related to the atomic number and end in -ium whether the element was expected to be a metal or not. The symbols have three letters, because any systematic set of two-letter symbols would tend to duplicate existing ones.
What are the rules?
From the same IUPAC document:
Roots: 0 nil, 1 un, 2 bi, 3 tri, 4 quad, 5 pent, 6 hex, 7 sept, 8 oct, 9 enn.
Order: put the roots together in the order of the digits and finish with -ium.
Spelling: the final n of enn is dropped before nil, and the final i of bi and tri is dropped before -ium.
Symbol: the initial letters of the roots, with the first letter capitalised.
The recommendation also says "un" is pronounced to rhyme with "moon", with each root said separately.
Worked examples
104: un + nil + quad + ium = unnilquadium, Unq. Now rutherfordium, Rf.
109: un + nil + enn + ium = unnilennium, Une. No rule applies: enn is followed by -ium, not nil.
111: un + un + un + ium = unununium, Uuu. Watch the spelling: three "un" roots then -ium, with no doubled n before the ending.
119: un + un + enn + ium = ununennium, Uue.
120: un + bi + nil + ium = unbinilium, Ubn. This is NCERT's Problem 3.1. Bi is followed by nil, so it keeps its i.
122: un + bi + bi + ium. The last bi meets -ium, so it becomes b: unbibium, Ubb.
123: un + bi + tri + ium, with tri losing its i: unbitrium, Ubt.
190: un + enn + nil + ium. Enn meets nil, so it becomes en: unennilium, Uen.
How do temporary names become permanent?
NCERT explains that once a discovery is confirmed, the element gets a permanent name and symbol through a vote of IUPAC representatives. The current procedure, How to name new chemical elements (IUPAC Recommendations 2016), says a joint IUPAC and IUPAP working group first confirms the discovery. The discoverers then propose a name, which can come from a mythological concept, a mineral, a place or country, a property or a scientist. The ending should in general be -ium for groups 1 to 16, -ine for group 17 and -on for group 18.
That rule explains the four names approved in 2016, listed in Öhrström and Reedijk (2016): nihonium (Nh, 113), moscovium (Mc, 115), tennessine (Ts, 117, a group 17 element) and oganesson (Og, 118, a group 18 element).
IUPAC's periodic table page gives its latest release as 4 May 2022 and does not list any named element beyond 118. If a question asks about element 119 or 120, use the systematic name.
Where would these elements sit?
NCERT's Problem 3.3 places element 120 in group 2, with the configuration [Og]8s², which NCERT writes as [Uuo]8s² using the old name for element 118. By the same logic, element 119 would start period 8 in group 1. Expect these as one-mark questions alongside the name.
Common mistakes
Writing "unbiium" or "untriium" instead of applying the i rule.
Writing "ennnil" with three n's.
Applying the enn rule before -ium, as in "unnilenium".
Using two-letter symbols for systematic names.
Mixing up digit order: element 109 is un-nil-enn, not enn-nil-un.
For naming organic compounds, which follows quite different rules, see our post on IUPAC naming of organic compounds. If periodic table ideas feel shaky in general, the Fermi Concept Library covers every concept in physics, chemistry, biology, mathematics and computing.
A practice routine
Write the ten roots from memory, twice.
Name and symbolise 105, 110, 118, 121, 129, 133 and 200. Check: unnilpentium Unp, ununnilium Uun, ununoctium Uuo, unbiunium Ubu, unbiennium Ube, untritrium Utt, binilnilium Bnn.
For each, mark whether a spelling rule applied.
Give the group number for elements 119 and 120.
Next time you open the periodic table, cover the names above 100 and rebuild three of them from their numbers.
