What it does
When a lab claims to have made a new, very heavy element, it can take years before the discovery is confirmed and the element gets its real name. Meanwhile chemists need to talk about it, so IUPAC gave a simple rule: build a temporary name from the digits of its atomic number. Each digit has a root (0 nil, 1 un, 2 bi, 3 tri, 4 quad, 5 pent, 6 hex, 7 sept, 8 oct, 9 enn), the roots are joined in order and “ium” is added at the end. The symbol is the first letter of each root.
This tool does it for any number from 100 to 999 and shows each digit and its root as a chip, the spelling rules where they apply, the real name if the element has one, and where it sits in the periodic table. You can also type a temporary name or symbol and read the number back.
It follows the school topic on the nomenclature of elements with atomic numbers greater than 100 (Class 11 Chemistry, classification of elements and periodicity). For the table itself see interactive periodic table, for the trends across it periodic trends, and for how Mendeleev predicted missing elements mendeleev's predictions.
How to use it
- Type an atomic number from 100 to 999, or use the slider or the − 1 and + 1 buttons.
- Read the chips (digit and root), the name and symbol, and the facts: the spelling rule used, the real name and the place in the table.
- Under Read a name back, type a temporary name (Unbiquadium) or symbol (Ubq) to get its number.
Worked example
Open the page: element 119. Its digits are 1, 1, 9, so the roots are un + un + enn, and with “ium” the name is Ununennium, symbol Uue. No one has made it yet; it would be the first element of period 8, in group 1 below francium.
Element 120 is un + bi + nil + ium = Unbinilium (Ubn). Element 122 shows the first spelling rule: un + bi + bi, and “bi” + “ium” becomes “bium”, so Unbibium (Ubb). Element 190 shows the second: un + enn + nil, and “enn” + “nil” becomes “ennil”, so Unennilium (Uen). Element 118 was called Ununoctium (Uuo) until 2016, when it was named oganesson (Og).
Tips
- Read a name from the left, one root at a time: Unbiquadium is un-bi-quad, 1-2-4, element 124.
- Every temporary symbol has three letters; every real symbol has one or two.
- The rule works for any number, but only elements up to 118 have been made so far.
FAQ
Why not just call it “element 119”? Chemists do, in speech; the systematic name and symbol give it a name that works in every language and in formulae.
Who chooses the real name? The discoverers propose a name, and IUPAC checks and approves it.
Is anything stored? No. It all runs in your browser.
Where the numbers come from
- IUPAC's 1978 recommendation for the systematic (temporary) names and symbols of elements with atomic numbers above 100: numerical roots nil, un, bi, tri, quad, pent, hex, sept, oct, enn plus the ending -ium, with the elisions bium, trium and ennil. General chemistry found in any textbook.
- Official names and symbols of elements 101 to 118: IUPAC, from the site's element list.
- Checked against the temporary names used before official naming (unnilquadium, ununnilium, ununoctium) and those still used for undiscovered elements (ununennium, unbinilium, unbiunium), and by reading the name and symbol of every number from 100 to 999 back to itself.
Standard scientific values, such as constants, atomic weights and melting points, are facts found in every textbook; we name where ours were checked. If you are an author or publisher and want a value, a credit or a table changed or removed, tell us and we will act quickly.
Last updated 2026-11-09.