Why is the atomic mass of radon unmeasured?

The measured atomic mass of an element is the effective average mass of that elements as found in laboratories. So if an element had two isotopes, one with an atomic mass of 200.0 and a frequency of 75%, and another with an atomic mass of 198. read more

It’s not that the atomic mass of radon is unmeasured. There are several isotopes of radon with varying degrees of stability. The atomic mass of radon is listed as 220 because it is the most stable isotope of radon with a half life of more than 2 days. read more

They were observing radon. That from radium was the longer-lived isotope radon-222 which has a half-life 3.8 days, and was the same isotope which the Curies has observed. The radon that Rutherford detected was radon-220 with a half-life of 56 seconds. read more

Radon is a gas, a member of the family of noble gases, radioactive, dangerous, practically nonreactive. Radon has 86 protons and 86 electrons, therefore the atomic number is 86. read more