Rubidium

In the earliest days of TARDIS technology, the fluid links primarily used validium but rubidium could be used as a substitute. Both were eventually retired when "the Other" convinced Rassilon that mercury was a safer alternative. (COMIC: The Lost Dimension)

v • e Elements

Periodic table	Hydrogen¹ Helium² Lithium³ Beryllium⁴ Boron⁵ Carbon⁶ Nitrogen⁷ Oxygen⁸ Fluorine⁹ Neon¹⁰ Sodium¹¹ Magnesium¹² Aluminium¹³ Silicon¹⁴ Phosphorus¹⁵ Sulphur¹⁶ Chlorine¹⁷ Argon¹⁸ Potassium¹⁹ Calcium²⁰ Titanium²² Vanadium²³ Chromium²⁴ Manganese²⁵ Iron²⁶ Nickel²⁸ Copper²⁹ Zinc³⁰ Gallium³¹ Germanium³² Arsenic³³ Bromine³⁵ Strontium³⁸ Zirconium⁴⁰ Molybdenum⁴² Rhodium⁴⁵ Palladium⁴⁶ Silver⁴⁷ Cadmium⁴⁸ Tin⁵⁰ Antimony⁵¹ Tellurium⁵² Caesium⁵⁵ Barium⁵⁶ Lanthanum⁵⁷ Neodymium⁶⁰ Promethium⁶¹ Terbium⁶⁵ Erbium⁶⁸ Thulium⁶⁹ Tantalum⁷³ Tungsten⁷⁴ Iridium⁷⁷ Platinum⁷⁸ Gold⁷⁹ Mercury⁸⁰ Lead⁸² Bismuth⁸³ Polonium⁸⁴ Astatine⁸⁵ Radon⁸⁶ Francium⁸⁷ Radium⁸⁸ Thorium⁹⁰ Uranium⁹² Neptunium⁹³ Plutonium⁹⁴ Californium⁹⁸ (Ek¹⁰⁴) Dubnium¹⁰⁵ Unniloctium¹⁰⁸ Ununquadium¹¹⁴ Ununhexium¹¹⁶ Unobservium¹¹⁹

Universal periodic table	Chaos matter

Greek elements	Water • Earth • Fire • Air

Chinese elements	Water • Earth • Fire • Wood • Metal

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