| 2025-10-27 | Chemical element whose name starts with an 8-point Scrabble letter |
| 2025-07-06 | Element in strobe lights |
| 2024-02-16 | Noble gas used in propelling ion thrusters |
| 2023-10-27 | Element exhibiting a blue glow when placed in an electric field |
| 2023-09-10 | Gas whose name comes from the Greek word for "foreigner" |
| 2023-01-01 | Noble gas used in some lasers |
| 2022-01-19 | Strobe light gas |
| 2021-08-22 | Member of a noble family |
| 2020-08-24 | Arc lamp gas |
| 2019-05-12 | Gas whose name comes from the Greek for "strange" |
| 2018-07-28 | Gas in arc lamps |
| 2017-11-08 | Element next to iodine on the periodic table |
| 2017-10-10 | This, on the periodic table |
| 2017-04-04 | Fifth member in a noble line |
| 2017-02-04 | Gas in an ion thruster |
| 2015-12-08 | Headlight gas |
| 2014-12-26 | First inert gas made into a compound |
| 2014-11-08 | Searchlight element |
| 2014-05-15 | Strobe light element |
| 2014-01-15 | Arc lamp gas |
| 2012-12-28 | It's a gas |
| 2012-08-08 | Arc lamp gas |
| 2012-03-31 | It's often in the spotlight |
| 2010-12-26 | Element in strobe lights |
| 2010-08-18 | Gas used in flash lamps |
| 2009-06-04 | Photographic flash gas |
| 2009-01-30 | 1980s Big Apple nightclub with a chemical name |
| 2008-12-15 | Gas in arc lamps |
| 2006-11-28 | An inert gas |
| 2005-07-03 | Element #54 |
| 2004-11-11 | Flash lamp filler |
| 2003-11-09 | Arc lamp gas |
| 2002-09-05 | It's a gas |
| 2001-12-04 | Arc lamp gas |
| 2001-04-17 | Element in arc lamps |
| 2001-02-14 | Hard-to-combine gas |
| 2000-01-02 | Radio tube filler |
| 1999-08-14 | It doesn't react well |
| 1997-10-08 | Element 54 |
| 1994-04-01 | TV tube material |