The letter "J" is the only one not found on the periodic table

Note that the letter "Q" does not appear in any official element names . Temporary element names, such as ununquadium, contain this letter. However, no element name starts with Q and no official element name contains this letter. Once the final four elements on the present periodic table get official names, there will be no Q on the periodic table. The extended periodic table, which includes undiscovered superheavy elements (atomic numbers greater than 118), would still contain the letter Q in temporary element names.