Radon
noble gas · period 6 · group 18 (noble gases) · p-block
Radon is a chemical element with the symbol Rn and atomic number 86. It is a radioactive, colorless, odorless, tasteless noble gas.
What the numbers say
At standard temperature and pressure Radon is a gas, sitting in period 6, group 18 of the p-block.
Its melting point of 202 K (-71 °C) is the 99th highest of the 110 elements with a measured value — mid-range among the elements.
At 0.01 g/cm³ it is the 86th densest of 96 elements with a quoted density.
Pauling electronegativity is 2.2. Paired with oxygen (3.44) that is a difference of 1.24, which puts the bond polar covalent — oxides here tend to be semiconducting or refractory rather than salt-like.
First identified in 1900.
Check it against computed structures
The structure search queries the Materials Project, OQMD and the Open Materials Database for computed crystal structures containing Rn — with DFT formation energy, hull stability and band gap where the provider publishes them.
K 2 · L 8 · M 18 · N 32 · O 18 · P 8
Properties
| Atomic number | 86 |
|---|---|
| Atomic mass | 222 u |
| Series | noble gas |
| Group | 18 |
| Period | 6 |
| Block | p-block |
| Phase at STP | Gas |
| Density | 0.01 g/cm³ |
| Melting point | 202 K (-71 °C) |
| Boiling point | 211.5 K (-62 °C) |
| Electronegativity (Pauling) | 2.2 |
| Electron configuration | [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁶ |
| Oxidation states | 2 |
| Discovered | 1900 |
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See Rn in context with all 118 elements.
Working with radon in a real design?
Ask the materials chat how Rn behaves in your alloy system, what it does to weldability, and which grades to look at — with the source of every number named.