Editing Xenon (section)

=== The missing Xe problem ===
The concentration of Xe in the atmosphere is much lower than Ar and Kr, a geological mystery known as "the missing Xe problem". Numerous proposals have been made to explain the mystery, including formation of Xe-Fe oxides in the Earth's lower mantle,<ref>{{Cite journal |last=Peng |first=Feng |last2=Song |first2=Xianqi |last3=Liu |first3=Chang |last4=Li |first4=Quan |last5=Miao |first5=Maosheng |last6=Chen |first6=Changfeng |last7=Ma |first7=Yanming |date=October 16, 2020 |title=Xenon iron oxides predicted as potential Xe hosts in Earth’s lower mantle |url=https://www.nature.com/articles/s41467-020-19107-y |journal=Nature Communications |language=en |volume=11 |issue=1 |doi=10.1038/s41467-020-19107-y |issn=2041-1723 |pmc=7568531 |pmid=33067445}}</ref> formation xenon dioxide in silica,<ref>{{Cite journal |last=Brock |first=David S. |last2=Schrobilgen |first2=Gary J. |date=April 27, 2011 |title=Synthesis of the Missing Oxide of Xenon, XeO2, and Its Implications for Earth’s Missing Xenon |url=https://pubs.acs.org/doi/10.1021/ja110618g |journal=Journal of the American Chemical Society |volume=133 |issue=16 |pages=6265–6269 |doi=10.1021/ja110618g |issn=0002-7863}}</ref> and reactions between Xe and Fe/Ni in the Earth's core.<ref>{{Cite journal |last=Zhu |first=Li |last2=Liu |first2=Hanyu |last3=Pickard |first3=Chris J. |last4=Zou |first4=Guangtian |last5=Ma |first5=Yanming |date=July 2014 |title=Reactions of xenon with iron and nickel are predicted in the Earth's inner core |url=https://www.nature.com/articles/nchem.1925 |journal=Nature Chemistry |language=en |volume=6 |issue=7 |pages=644–648 |doi=10.1038/nchem.1925 |issn=1755-4349|arxiv=1309.2169 }}</ref>