86
Room of the Elements · No. 86
Radon (Rn): what kind of element is it?
日本語
In short
Radon is element number 86, with the symbol Rn. Its name combines “radium” and “emanation.”
Atomic number 86(222)
RnRadonラドン (radon)- Symbol
- Rn
- Atomic weight
- (222)
- Place in the table
- Period 6 · Group 18
The number in parentheses is not an atomic weight. It is the mass number of one radioactive isotope of the element.
Atomic weight from the Chemical Society of Japan, “Table of Standard Atomic Weights with Four Significant Figures (2026)”.
Radium and “emanation”
Radon was discovered in 1900. Its name combines radium, which the Curies had found in 1898, with the Latin word for “emanation.”
At the bottom of Group 18
Radon is in the sixth row of Group 18, a noble gas like helium, neon, argon, krypton and xenon.
Think about it
- Q1Why do you think its name was based on radium?
- Q2Can you name all the Group 18 noble gases from the top?
- Q3Collect the name origins of the noble gases in the Room of the Elements.
There is no single right answer. Talking it over with someone at home is a good way to learn.
Did you know? — The Group 18 names come from: helium (the Sun), neon (new), argon (idle), krypton (hidden), xenon (stranger) and radon (radium).