Ek

Ek was the symbol of an element on the periodic table with an atomic number of 104. (TV: Shada)

Behind the scenes
Element 104 was first synthesised in in the 1960s and named (Rf) in 1997, decades after the 1979 setting of the television story Shada. The element was temporary named unnilquadium (Unq) but was also known as eka-hafnium.