BROMINE

Set to 3 different clues across 3 published puzzles, most often “Element used in fire retardants” — The New York Times, Thursday, 1 October 2009.

7 letters

Every clue on record, most used first

Element used in fire retardantsonce
The New York Times — Thursday, 1 October 2009
Element that's liquid at room temperatureonce
The New York Times — Sunday, 23 September 2007
No. 35 on the periodic tableonce
The New York Times — Wednesday, 24 November 1999