Historical clue formulations

• Chemical element whose name starts with an 8-point Scrabble letter — 2025-10-27
• Element in strobe lights — 2025-07-06
• Noble gas used in propelling ion thrusters — 2024-02-16
• Element exhibiting a blue glow when placed in an electric field — 2023-10-27
• Gas whose name comes from the Greek word for "foreigner" — 2023-09-10
• Noble gas used in some lasers — 2023-01-01
• Strobe light gas — 2022-01-19
• Member of a noble family — 2021-08-22
• Arc lamp gas — 2020-08-24
• Gas whose name comes from the Greek for "strange" — 2019-05-12
• Gas in arc lamps — 2018-07-28
• Element next to iodine on the periodic table — 2017-11-08
• This, on the periodic table — 2017-10-10
• Fifth member in a noble line — 2017-04-04
• Gas in an ion thruster — 2017-02-04
• Headlight gas — 2015-12-08
• First inert gas made into a compound — 2014-12-26
• Searchlight element — 2014-11-08
• Strobe light element — 2014-05-15
• Arc lamp gas — 2014-01-15
• It's a gas — 2012-12-28
• Arc lamp gas — 2012-08-08
• It's often in the spotlight — 2012-03-31
• Element in strobe lights — 2010-12-26
• Gas used in flash lamps — 2010-08-18
• Photographic flash gas — 2009-06-04
• 1980s Big Apple nightclub with a chemical name — 2009-01-30
• Gas in arc lamps — 2008-12-15
• An inert gas — 2006-11-28
• Element #54 — 2005-07-03
• Flash lamp filler — 2004-11-11
• Arc lamp gas — 2003-11-09
• Arc lamp gas — 2001-12-04
• Element in arc lamps — 2001-04-17
• Hard-to-combine gas — 2001-02-14
• Radio tube filler — 2000-01-02
• It doesn't react well — 1999-08-14
• Element 54 — 1997-10-08
• TV tube material — 1994-04-01