Periodic Table


Atomic number: 86
Atomic weight: 222
Symbol: Rn
Group number: 18
Electronic configuration: [Xe].4f14.5d10.6s2.6p6


At ordinary temperatures radon is a colourless gas. When cooled below the freezing point, radon exhibits a brilliant phosphorescence which becomes yellow as the temperature is lowered and orange-red at the temperature of liquid air.

The main hazard is from inhalation of the element and its decay products which are collected on dust in the air. Recently, radon buildup in homes from the surrounding soil and rocks has become a safety issue and some areas around the world test homes for radon gas. It is the heaviest known gas. Radon is present in some spring waters.

General information

Discoveror: Friedrich Ernst Dorn
Date discovered: 1900
Discovered at: Germany
Meaning of name: Named after "the element radium" (radon was called niton at first, from the Latin word "nitens" meaning "shining"

Physical data

Standard state: E0


This section gives some data for naturally occurring isotopes.
Nominal mass Accurate mass % natural abundance

Further Information

Copyright 1997 Mark Winter
Department of Chemistry at the University of Sheffield, Sheffield S3 7HF, England.

The current version of this document is at http://www.shef.ac.uk/~chem/web-elements-I/Rn.html