a naturally occurring radioactive isotope of thorium. Symbol: Io; atomic number: 90; atomic weight: 230.
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How to use ionium in a sentence
ionium expels an alpha particle and becomes radium, which is a bivalent element resembling barium belonging to the second group.A Brief Account of Radio-activity | Francis Preston Venable
British Dictionary definitions for ionium
obsolete a naturally occurring radioisotope of thorium with a mass number of 230: Symbol: Io
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012