radonnoun [ U ]
uk/ˈreɪ.dɒn/us/ˈreɪ.dɑːn/symbol Rna chemical element that is a radioactive gas formed when radium decays and found naturally in rock and soil:
Tests showed high radon levels.
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Chemical elements
- alkali metal
- antimony
- calcium
- carbonic
- carbonic acid
- cesium
- cl
- graphene
- lithium
- nickel
- plutonium
- quicksilver
- sodium
- strontium
- sulphur
- transition metal
- tungsten
- urea
- vanadium
- zinc
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