| 2021-08-28 | The chloride in sodium chloride, e.g. |
| 2020-11-13 | I-, for one |
| 2020-06-14 | Bit of negativity? |
| 2018-09-05 | Particle with a negative charge |
| 2018-05-17 | Negative particle |
| 2018-01-26 | Atom with an electronic imbalance |
| 2016-05-05 | Fluoride, e.g. |
| 2015-05-22 | F-, H- or I-, but not G- |
| 2014-01-17 | It's written with a minus sign |
| 2013-12-11 | OH- or Cl-, chemically |
| 2013-01-06 | Bit of negativity? |
| 2012-12-15 | F-, for one |
| 2012-02-15 | OH- or Cl-, chemically |
| 2012-02-03 | Fluoride, e.g. |
| 2009-07-15 | Chloride or carbonate |
| 2008-08-27 | Negative particle |
| 2008-05-18 | Electrolysis particle |
| 2008-04-11 | It's negative |
| 2007-05-22 | Charged particle |
| 2007-03-03 | Electrolysis particle |
| 2006-09-10 | Electrolysis particle |
| 2005-10-14 | It's negative |
| 2005-06-18 | Part of an electrolytic exchange |
| 2004-06-28 | Negatively charged particle |
| 2004-03-05 | Electrolysis particle |
| 2003-04-12 | It's involved in electrolysis |
| 2002-07-26 | Cl-, e.g. |
| 2002-03-18 | Particle in electrolysis |
| 2001-08-19 | It has a negative charge |
| 2000-03-15 | Negative particle |
| 1999-12-22 | CH-, e.g. |
| 1999-05-31 | Negatively charged particle |
| 1996-06-11 | Charged atom |
| 1996-01-06 | Hydroxide particle |
| 1995-12-01 | Electrolysis particle |
| 1995-09-08 | Electrolysis particle |
| 1994-01-16 | Electrolysis particle |