The letters J and Q are the only two letters that do not appear in the names or official symbols of any of the 118 chemical elements on the modern periodic table. These letters do not occur in either element symbols or element names. However, you could find both letters on the periodic table in the past and may find them still on certain charts.
Quick Answer
| Question | Answer |
|---|---|
| Which letters are missing from the periodic table? | J and Q |
| Are they missing from element symbols? | Yes |
| Are they missing from element names? | Yes |
| Has J ever appeared? | Yes, historically as the symbol for iodine (Jod) |
| Has Q ever appeared? | Only in temporary IUPAC names such as ununquadium |
Key Takeaways: What Letter Is not on the Periodic Table?
- J and Q are the only letters missing from the names and symbols of the 118 known elements.
- J appeared on older periodic tables because iodine was written as Jod in several languages.
- Q has never appeared in an official element name, but it is used in IUPAC temporary names such as ununquadium.
- Future element discoveries could introduce the letter J if discoverers choose an appropriate name.
- The letter Q is much less likely to become permanent because IUPAC naming traditions rarely produce names containing Q.
The Letter J on the Periodic Table
While the letter J does not appear in any official modern element name or symbol, J was the symbol for the element jod or iodine on Mendeleev’s periodic table. In some countries (e.g., Norway, Poland, Sweden, Serbia, Croatia), the element iodine is known by the name jod, even though the international element symbol is I. The German word for iodine is Iod or Jod (nouns are always capitalized in German). The Jod-Basedow effect gets its name from the element Jod and the name of the physician who first described the syndrome. The Jod-Basedow effect is is iodine-induced hyperthyroidism.
Many people thought the discovery of element 113 by the Japanese RIKEN team would lead to an element name beginning with the letter J. But, the researchers went with the name nihonium with symbol Nh, honoring the Japanese name for their country, Nihon koku.
Could J Appear on the Periodic Table Again?
Yes.
IUPAC allows discoverers of new elements to propose names honoring a scientist, place, mineral, property, or mythological concept. If a future element were given a name beginning with J, its symbol would likely include the letter as well.
Many chemistry enthusiasts once speculated that element 113 might receive a Japanese-inspired name beginning with J, but the discoverers chose nihonium (Nh) instead, using the Japanese word Nihon for Japan.
The Letter Q on the Periodic Table
Unlike J, the letter Q has never appeared in the official name or symbol of any chemical element.
However, Q does appear in temporary systematic names assigned by IUPAC before newly discovered elements receive permanent names. The temporary name for element 114 was ununquadium (Uuq) before it became flerovium (Fl) in 2012.
Because the temporary root for the digit 4 is quad, any placeholder name containing the number 4 includes the letter Q.
Examples include:
- ununquadium (114)
- unbiquadium (124)
- unquadhexium (146)
Once an element receives its permanent name, the temporary name is retired.
IUPAC Rules for Temporary Names
IUPAC temporary names describe undiscovered elements by their atomic number. The only way an element will get a “J” in its name is if a discoverer chooses the letter, but the letter “Q” occurs in any temporary name containing the number four:
| Digit | Root | Symbol |
| 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 |
| Suffix | -ium | none |
Why Doesn’t Any Element Use J or Q?
There is no rule prohibiting either letter.
Instead, it is simply the result of history and language.
Most element names originate from:
- Latin
- Greek
- Scientists’ names
- Places
- Minerals
- Mythology
These naming traditions rarely produce the letters J or Q. The absence of both letters is therefore an historical coincidence rather than an intentional design of the periodic table.
What About the Letter W?
Unlike J and Q, the letter W does appear on the periodic table, but only in limited ways.
The element tungsten has the symbol W, which comes from its historical German name Wolfram. The English name tungsten contains no W, but the international chemical symbol preserves the older name.
Among the 118 official English element names, lawrencium is the only one that contains the letter W. So while W is rare in element names, it is not missing from the periodic table.
Frequently Asked Questions
What letters are not on the periodic table?
Only J and Q are absent from the names and symbols of all 118 officially recognized chemical elements.
Has J ever been on the periodic table?
Yes. Some historical periodic tables used J as the symbol for iodine because the element was known as Jod in German and several other European languages.
Has Q ever been an element symbol?
No. Q has appeared only in temporary IUPAC names such as ununquadium, not in permanent element names or symbols.
Could a future element contain J?
Yes. If the discoverers propose an IUPAC-approved name containing J, the letter could appear on future periodic tables.
Could Q become part of a permanent element name?
It is possible but unlikely. Existing naming traditions have not produced an approved element name containing Q.
References
- El-Shirbiny, A.M.; Stavrou, S.S.; Det al. (November 1997). “Jod-Basedow syndrome following oral iodine and radioiodinated-antibody administration.” J. Nucl. Med. 38 (11): 1816–7.
- Mendeleev, Dmitrii. (1871). Zhurnal Russkoe Fiziko-Khimicheskoe Obshchestvo 3, 25; German version: “Die periodische Gesetzmässigkeit der chemischen Elemente.” Annalen der Chemie und Pharmacie. Supplement 8, 133-229.
- Mendeleev, Dmitrii (1889). “The Periodic Law of the Chemical Elements.” Journal of the Chemical Society (London) 55, 634-656.