Señor 105 was a Mexican luchador from the 1960s who had a mask for every element stored in cubbyholes arranged in shape of the periodic table. He made a new mask and added another number to his name following the discovery of each new element. (PROSE: Iris Wildthyme y Señor Cientocinco contra Los Monstruos del Fiesta)
There were at least 118 elements on the periodic table. Physicist Ed claimed to have created element 119 of the periodic table on at least three occasions — although the atoms never lasted more than two picoseconds — and wanted to name it Unobservium before it was properly discovered. He believed it was a better name than ununquadium or ununhexium. (PROSE: The Big Crunch)
According to the Fourth Doctor, the periodic table was first published in 1872 and had many scientific revelations in it. When archaeologist Horace Stockwood wasn't familiar with it, the Doctor stated that "anyone who claims to be a scientist and who hasn't heard of the periodic table is not so much walking as crawling - rather rapidly back into the Dark Ages." (PROSE: Eye of Heaven)
In the 1955, ten-year-old Henry Bergson wanted a chemistry set for Christmas but his father didn't believe in him and claimed he couldn't afford it. In this timeline, Henry Bergson ended up homeless by 1975 but could still remember every component of the set, including a poster of the periodic table. The Seventh Doctor and his companions altered the timeline by giving Henry the chemistry set as a child, leading to him becoming an important biologist whose research defeated a Kellenian invasion of Earth. (PROSE: Presence)
In 1979, there was a periodic table labelled with atomic numbers on the wall of Chris Parsons' lab. It listed 104 elements, with element 105 left blank. (TV: Shada) Element 105 was disovered in 1968 and named dubnium in the 1990s. (PROSE: Iris Wildthyme y Señor Cientocinco contra Los Monstruos del Fiesta)
with atomic numbers
When history teacher Barbara Wright teased Ian Chesterton for not having learned the British monarchy as a schoolboy, the science teacher retorted about schoolgirls not learning the periodic table. (PROSE: The Plotters)
When the Eighth Doctor had partial amnesia following his destruction of Gallifrey, he could remember "useless bits of information" like the periodic table. (PROSE: Halflife) He could even sing the periodic table to the tune of "The Modern Major General". (PROSE: Grimm Reality) While stranded on Earth, the Doctor hid a safe behind a framed copy of the periodic table in the 1980s. (PROSE: Father Time)
Archaeologist Ernest Fleetward discovered parts of a humanoid skeleton around the world made of crystals which did not fit in the periodic table and established crystallography. The Eighth Doctor convinced him to present his findings in early 2004. (PROSE: Sometime Never...)
Technical Services Supervisor Alex Bannen analyses indicated all super-heavy elements of the periodic table were abundant on Lucifer and were used to power the Lift and Moloch's interior sun. His goal for Project Eden was to get the Angels to tell him how and where they were produced and stabilized as well as obtaining samples. (PROSE: Lucifer Rising)
Chief Scientist Whitfield could recite the whole periodic table as a child. This fact helped her know she was the same person after using a transmat that broke her body down at one end and reassembled it on the other. (PROSE: Cold Fusion)
Chaos matter was an element on the universal periodic table, which could be used to disrupt the gravity of entire planets. The element was found exclusively on the planet Alma. (PROSE: A Bright White Crack)
Behind the scenes
- The periodic table the Fourth Doctor is referring to in PROSE: Eye of Heaven was actually published a year earlier, in 1871.
- The Eighth Doctor references "The Elements" by Tom Lehrer in PROSE: Grimm Reality.
- The periodic table seen in TV: Shada shows element 104 (Ek) in place of Rutherfordium (Rf), a possible reference to its hypothetical name: eka-hafnium.
- The poster seen in Class is the Royal Society of Chemistry Periodic Table Wallchart. It appears to be the 2013 version, as the version with elements named in 2016 was released in early 2017 after the series was filmed, and indeed before it aired.
- Zoe said 50 in the episode, cutting herself off when she saw a Kroton. She finishes saying 52 in the novelisation.