Francium Fr (Element 87) of Periodic Table

87 Fr (Francium)

Appearance:  An intensely radioactive metal.

Mass number:  223

Atomic weight:  223.0197 g/mol

Atomic number (Z):  87

Electrons:  87

Protons:  87

Neutrons:  136

Group:  1

Period:  7

Block:  S

Element category:  Alkali

Electrons per shell:  K2, L8, M18, N32, O18, P8, Q1

Electron configuration:  1s22s22p63s23p63d104s24p64d105s25p64f145d106s26p67s1

Phase:  Solid

Melting point:  300 K (27 oC)

Boiling point:  950 K (677 oC)

Density:  2.8 – 3.0 g/cm3

Half Life(s):  1300

Lifetime (s):  1900

Decay mode:  β decay

Oxidation states:  +1

Ion charge:  Fr+ 

Electronegativity:  Pauling scale: >0.79

Valence:  3

Ionization energies:  1st: 393 kJ/mol

Covalent radius:  260 pm

Vander waals radius: 348 pm

Crystal structure:  Body centered cubic

Thermal conductivity:  15 W/(m∙K)

Electrical resistivity:  3μΩ∙m

Magnetic ordering:  Paramagnetic

CAS Number:  7440-73-5

Naming:  After France (Homeland of the discoverer)

Discovery & 1st isolation:  Marguerite Perey (1939)

Isotopes:  221Fr 222Fr 223Fr

Uses:  It has no uses

Biological role:   It is toxic due to its radioactivity

Natural abundance:  It is obtained by the neutron bombardment of radium in a nuclear reactor and  It can also be made by bombarding thorium with protons.


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