Strange elements tend to have properties that make them extremely difficult to study. For example, Copernicium has a half-life of only 29 seconds, and Francium would probably explode upon contacting the moisture in the air.
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Key Facts In This Video
Gallium safely melts in human hands. 00:44
Francium has never been visible to the naked eye. 03:08
When sufficiently cooled, Helium becomes a superfluid that seemingly defies gravity. 06:10