*5: A trivalent element or [[radical]], i.e. one which combines with [[three]] [[atoms]] of [http://en.wikipedia.org/wiki/Hydrogen hydrogen] or other monovalent element or radical. | *5: A trivalent element or [[radical]], i.e. one which combines with [[three]] [[atoms]] of [http://en.wikipedia.org/wiki/Hydrogen hydrogen] or other monovalent element or radical. |