Fr

Francium · element 87

Alkali Metal · Solid at room temperature

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.

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This is only an illustration, not francium itself.
This is only an illustration, not francium itself. - Chemical ELements A Virtual Museum, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0> source: https://images-of-elements.com/francium.jpg

Key facts

Atomic mass
223 u
how heavy one atom is
Phase (room temp.)
Solid
Density
1.87 g/cm³
how tightly packed it is
Melting point
300 K (27 °C)
when solid turns to liquid
Boiling point
950 K (677 °C)
when liquid turns to gas
Period
7
its row in the periodic table
Group
1
its column in the periodic table
Block
S-block
the neighbourhood it lives in
Electronegativity
0.79
how strongly it pulls electrons
Electron configuration
[Rn] 7s1
where its electrons live
Shells
2 · 8 · 18 · 32 · 18 · 8 · 1
electrons in each layer, inside to out
Discovered by
Marguerite Perey
who found it

Source: Wikipedia

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