Isotopes of radium

Radium (₈₈Ra) has no stable or nearly stable isotopes, and thus a standard atomic weight cannot be given. The longest lived, and most common, isotope of radium is ²²⁶Ra with a half-life of 1600 years, which is in the decay chain of ²³⁸U (the uranium or radium series).

Radium now has 34 known isotopes from ²⁰¹Ra to ²³⁴Ra.

In the early history of the study of radioactivity, the different natural isotopes of radium were given different names (as were those of other radioactive elements), as it was not until Frederick Soddy's scientific work in the 1900s and 1910s that the concept of isotopes was employed.^[3] In this scheme, ²²³Ra was named actinium X (AcX), ²²⁴Ra thorium X (ThX), ²²⁶Ra radium (Ra), and ²²⁸Ra mesothorium 1 (MsTh₁).^[4] When it was realized that all of these are isotopes of the same element, many of these names fell out of use, and "radium" came to refer to all isotopes, not just ²²⁶Ra,^[5] though mesothorium 1 in particular was still used for some time, with a footnote explaining that it referred to ²²⁸Ra.^[6] The known decay products of radium-226 received historical names including "radium",^[7] starting with radium emanation and then ranging from radium A to radium G, with the letter indicating approximately how far they were down the chain from their parent.^[a]

In 2013 it was discovered that the nucleus of radium-224 is pear-shaped.^[9] This was the first discovery of an asymmetrical nucleus.

• 同位体質量は以下から得られます。
  • アウディ、ジョルジュ。ベルシヨン、オリヴィエ。ジャン・ブラショー。Wapstra、Aaldert Hendrik (2003)、 「核および崩壊特性のN UBASE評価」 、核物理学 A、729 : 3–128、Bibcode : 2003NuPhA.729....3A、doi : 10.1016/j.nuclphysa.2003.11.001
• 半減期、スピン、および異性体データは、以下の情報源から選択した。
  • アウディ、ジョルジュ。ベルシヨン、オリヴィエ。ジャン・ブラショー。Wapstra、Aaldert Hendrik (2003)、 「核および崩壊特性のN UBASE評価」 、核物理学 A、729 : 3–128、Bibcode : 2003NuPhA.729....3A、doi : 10.1016/j.nuclphysa.2003.11.001
  • 国立核データセンター。「NuDat 3.0データベース」。ブルックヘブン国立研究所。
  • ホールデン、ノーマン E. (2004). 「11. 同位体表」。デイビッド R. リデ編『CRC化学物理ハンドブック（第85 版）』所収。フロリダ州ボカラトン：CRC Press。ISBN 978-0-8493-0485-9。