Francium

Neutral francium atoms can be trapped in the MOT using a magnetic field and laser beams.[35]

Image of light emitted by a sample of 200,000 francium atoms in a magneto-optical trapHeat image of 300,000 francium atoms in a magneto-optical trap

Francium is a chemical element with symbol Fr and atomic number 87. It used to be known as eka-caesium and actinium K. It is the second-least electronegative element, behind only caesium. Francium is a highly radioactive metal that decays into astatine, radium, and radon. As an alkali metal, it has one valence electron.

单词	Russium
释义	Russium 英语百科 Francium Francium is a chemical element with symbol Fr and atomic number 87. It used to be known as eka-caesium and actinium K. It is the second-least electronegative element, behind only caesium. Francium is a highly radioactive metal that decays into astatine, radium, and radon. As an alkali metal, it has one valence electron.
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Russium

Francium