QCC Notes
CLASS 11 · CHEMISTRYJEE MAIN × NEETहिंदी
§ 3.3NCERT Class 11 · Chemistry · Chapter 3

Nomenclature of Elements with Atomic Numbers > 100

Superheavy elements triggered a Cold War of names — two countries, two names, one element. IUPAC’s truce: ten digit roots that give every element from 100 to 999 a neutral, temporary name, no diplomacy required. Ten roots, two spelling rules, one live decoder.

QCC Notes · Class 11 Chemistry NCERT-aligned Updated 26 Sep 2026 12 min read
01

Why New Names Were Needed — Complete Theory

Synthesis raced ahead of diplomacy. When labs in different countries claimed the same new superheavy element, each proposed its own name: element 104 was rutherfordium to the Americans and kurchatovium to the Soviets; element 105 was hahnium to one camp and nielsbohrium to another. Textbooks split, students suffered, and the table grew embarrassing footnotes. IUPAC’s fix: a neutral, systematic temporary name derived mechanically from the atomic number — used until the discovery claim is settled and a permanent name is agreed (most were, by 1997).

The machinery is delightfully small. Ten digit-roots stand for the digits 0–9; the digits of the atomic number are replaced by their roots in order; the ending -ium is appended for the name; and the first letters of the roots form a three-letter temporary symbol (first letter capitalised).

Table 1 — The digit roots: 0 → 9 (memorise root and letter together)
DigitRootLetterDigitRootLetter
0niln5pentp
1unu6hexh
2bib7septs
3trit8octo
4quadq9enne
Table 2 — NCERT’s worked examples: temporary → permanent
ZTemporary nameSymbolPermanent namePermanent symbol
101unniluniumUnuMendelevium (Md)
102unnilbiumUnbNobelium (No)
103unniltriumUntLawrencium (Lr)
109unnilenniumUneMeitnerium (Mt)
110ununniliumUunDarmstadtium (Ds)
111unununiumUuuRoentgenium (Rg)

Two spelling adjustments keep the names pronounceable, and both are exam favourites: when enn (9) is followed by nil (0), one “n” is dropped — enn + nil → ennil, so 190 is unennilium, not “unennnilium”; and when bi (2) or tri (3) is followed by the ending -ium, one “i” is dropped — bi + ium → bium, tri + ium → trium, so 112 is ununbium and 113 is ununtrium. Crucially, the symbol ignores these adjustments — it always reads the raw digit-roots: 190 is Uen (u-e-n) even though its name spells “ennil”.

02

Visualising the Pipeline & Decoding Any Z

Ek pipeline, ek decoder — watch 109 build itself first, then feed the decoder any Z from 101 to 199.

Element 109 on the naming pipeline — digits to roots to name and symbol FIG. 1 — THE NAMING PIPELINE, WORKED ON Z = 109 1 · 0 · 9digits of Z = 109 un · nil · enndigit roots, in order Unesymbol: 1st letters unnilenniumroots + “-ium” spelling rules: enn + nil → ennil (drop one “n”) · bi/tri + ium → bium/trium (drop one “i”) SECOND LANE — Z = 190, where the rule actually fires 1 · 9 · 0 un · enn · nil unennilium enn+nil → ennil Uen symbol: raw u-e-n symbol roots the digits — spelling bends, symbol doesn’t
FIG. 1 — Two lanes, one law: 109 runs clean to unnilennium / Une; 190 forces the “enn + nil → ennil” adjustment yet keeps symbol Uen — because the symbol reads digits, never adjusted spelling.
Try it live

Nomenclature Decoder

Z = 110Symbol: Uun

Digits1 · 1 · 0
Roots (raw)un · un · nil
Statuspermanently named

Spelling adjustments fire live: watch “nnn → nn” on 190 and “ii → i” on 102/103/112/113 — while the symbol keeps the raw digit-roots. For Z ≥ 119 the temporary name is the only name that exists.

03

Solved Examples (Step-by-Step)

Digits → roots → name → symbol. Jo chain yahan chalti hai, wahi decoder me live chalti hai.

EXAMPLE 01Foundation · Clean build

Z = 114, no adjustments needed

Write the temporary IUPAC name and symbol for the element with Z = 114, and give its permanent name.

  1. Digits1, 1, 4 → roots un, un, quad
  2. Name+ ium → ununquadium — quad ends in “d”, no “ii” clash, rule-free ✓
  3. Symbolu + u + q → Uuq
  4. PermanentSettled as Flerovium (Fl) — verify on the decoder.

ununquadium (Uuq) → Flerovium (Fl)

EXAMPLE 02JEE Main · The rule fires

Z = 190: where “nnn” must shrink

Write the temporary name and symbol for Z = 190, showing the spelling adjustment explicitly.

  1. Digits1, 9, 0 → roots un, enn, nil
  2. Raw join+ ium → unennnilium — contains the illegal triple-n.
  3. Adjustenn + nil → ennil (drop one “n”) → unennilium
  4. SymbolDigit-letters u, e, n → Uen — not “Unn”: the symbol reads digits, ignoring the adjusted spelling.

unennilium · symbol Uen — rule fired, symbol unbothered

EXAMPLE 03JEE Main · Reverse decode

From “unbihexium” back to Z

An old problem sheet refers to “unbihexium (Ubh)”. Recover its atomic number and say whether it has a permanent name.

  1. Split rootsun · bi · hex → digits 1, 2, 6
  2. ZZ = 126 — symbol check: u-b-h → Ubh ✓
  3. StatusZ = 126 lies beyond 118 — never synthesised, so the temporary name is its only name. Reverse decoding is how examiners test the root table itself.

Z = 126 · Ubh — unnamed, and correctly so

04

Practice Questions (With Solutions)

Attempt first — options lock after one shot, exactly like the real exam. Then read the working, chahe galti ho ya na ho.

Attempted 0/4 · Correct 0

Q1NEET · Build a name

The IUPAC temporary name and symbol for the element with Z = 111 are:

Solution

  1. 111 → 1,1,1 → un·un·un + ium = unununium, symbol Uuu — now roentgenium (Rg).
  2. Option A is 110’s name; C is 109’s; D is 112’s — the decoder catches all three instantly.

(B) unununium, Uuu

Q2JEE Main · Spelling rule

When the root “enn” is followed by the root “nil”, the combined name:

Solution

  1. Exactly one “n” is dropped: enn + nil = ennil — so 190 is unennilium.
  2. The letter-count must stay sensible; and the symbol still reads the raw digits (Uen), whatever the spelling does.

(B) Drop one n → ennil

Q3JEE Main · Build with a rule

The temporary name of the element with Z = 120 is:

  1. 120 → 1,2,0 → un·bi·nil + ium. “bi” is followed by “nil”, not by “ium” — no i-drop fires → unbinilium.
  2. Symbols are always three letters (B is wrong twice); the leading “un” for digit 1 is never optional (D).

(A) unbinilium (Ubn)

Q4NEET · Reverse

The temporary symbol “Ubh” corresponds to the atomic number:

  1. U-b-h → u = 1, b = 2, h = 6 → Z = 126 (unbihexium).
  2. Option A reverses the digit order; C reads letters as numbers; D misreads h as 9.

(B) 126

05

Key Rules & Takeaways

Root card

Eight lines that solve this topic

Why: discovery disputes (Rf vs Ku)Competing claims → IUPAC’s neutral placeholder system.
Roots: 0 nil · 1 un · 2 bi · 3 tri4 quad · 5 pent · 6 hex · 7 sept · 8 oct · 9 enn.
Name = roots (digit order) + ium110 → un·un·nil·ium = ununnilium.
Symbol = 1st letters of roots, 3 lettersCapitalise first: 109 → Une.
enn + nil → ennil (drop one n)190 = unennilium — not “unennnilium”.
bi/tri + ium → bium/trium (drop one i)112 = ununbium · 113 = ununtrium.
Symbol ignores spelling adjustments190: name “ennil” but symbol Uen — digits decide.
Temporary → permanent after settlement101–118 all settled (Md…Og); Z ≥ 119: temp name is the only name.

Disputes: 104 rutherfordium vs kurchatovium · 105 hahnium vs nielsbohrium  ·  NCERT examples: 101 Unu · 102 Unb · 103 Unt · 109 Une · 110 Uun · 111 Uuu

  1. Ten roots name nine hundred elements — the whole system is a digit-to-syllable cipher with an -ium tail.
  2. Two adjustments, two vowels — enn+nil drops an “n”; bi/tri+ium drops an “i”. Quote them exactly; they are one-mark questions.
  3. Symbol and spelling live apart — the symbol reads raw digit-roots (190 → Uen), the name takes the pronounceable form (unennilium).
  4. Temp names are scaffolding — 101–118 now carry permanent names; for never-made elements (Z ≥ 119), the temporary name is the only name.
06

FAQs

Why were systematic temporary names needed for elements with Z > 100?

Discoveries of superheavy elements often involved competing claims from laboratories in different countries, and each lab proposed its own name — element 104 was called rutherfordium by Americans and kurchatovium by Soviet scientists. To end such disputes, IUPAC adopted a neutral, systematic naming scheme: a temporary name built from digit roots, used until the discovery claim is settled and a permanent name is agreed.

What are the IUPAC digit roots from 0 to 9?

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) and 9 = enn (e). The digits of the atomic number are replaced by these roots in order, the ending -ium is added for the name, and the first letters of the roots give the three-letter temporary symbol.

What is the temporary name and symbol of element 110?

Element 110 = digits 1, 1, 0 = un + un + nil + ium = ununnilium, with the temporary symbol Uun. It has since received the permanent name darmstadtium (Ds). Similarly, 111 = unununium (Uuu), now roentgenium (Rg).

What spelling adjustments apply when combining the digit roots?

Two adjustments apply: when enn (9) is followed by nil (0), one n is dropped — enn + nil = ennil, so 190 is unennilium, not unennnilium; and when bi (2) or tri (3) is followed by the ending -ium, one i is dropped — bi + ium = bium and tri + ium = trium, so 112 is ununbium and 113 is ununtrium. The three-letter symbol, however, always uses the raw digit roots.

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