Francium

  • francium, 87fr
    francium
    pronunciationm/ (fran-see-əm)
    mass number[223]
    francium in the periodic table
    hydrogen helium
    lithium beryllium boron carbon nitrogen oxygen fluorine neon
    sodium magnesium aluminium silicon phosphorus sulfur chlorine argon
    potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton
    rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon
    caesium barium lanthanum cerium praseodymium neodymium promethium samarium europium gadolinium terbium dysprosium holmium erbium thulium ytterbium lutetium hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury (element) thallium lead bismuth polonium astatine radon
    francium radium actinium thorium protactinium uranium neptunium plutonium americium curium berkelium californium einsteinium fermium mendelevium nobelium lawrencium rutherfordium dubnium seaborgium bohrium hassium meitnerium darmstadtium roentgenium copernicium nihonium flerovium moscovium livermorium tennessine oganesson
    cs

    fr

    (uue)
    radonfranciumradium
    atomic number (z)87
    groupgroup 1: h and alkali metals
    periodperiod 7
    blocks-block
    element category  alkali metal
    electron configuration[rn] 7s1
    electrons per shell2, 8, 18, 32, 18, 8, 1
    physical properties
    phase at stpsolid at 0 °c, liquid at r.t.
    melting point281.0 k ​(8.0 °c, ​46.4 °f) (estimated)[1]
    boiling point890 k ​(620 °c, ​1150 °f) (estimated)[1]
    density (near r.t.)2.48 g/cm3 (estimated)[1]
    vapor pressure (extrapolated)
    p (pa) 1 10 100 1 k 10 k 100 k
    at t (k) 404 454 519 608 738 946
    atomic properties
    oxidation states+1 (a strongly basic oxide)
    electronegativitypauling scale: >0.79
    ionization energies
    • 1st: 393 kj/mol[2]
    covalent radius260 pm (extrapolated)
    van der waals radius348 pm (extrapolated)
    other properties
    natural occurrencefrom decay
    crystal structurebody-centered cubic (bcc)
    body-centered cubic crystal structure for francium

    (extrapolated)
    thermal conductivity15 w/(m·k) (extrapolated)
    electrical resistivity3 µΩ·m (calculated)
    magnetic orderingparamagnetic
    cas number7440-73-5
    history
    namingafter france, homeland of the discoverer
    discovery and first isolationmarguerite perey (1939)
    main isotopes of francium
    iso­tope abun­dance half-life (t1/2) decay mode pro­duct
    212fr syn 20.0 min β+ 212rn
    α 208at
    221fr trace 4.8 min α 217at
    222fr syn 14.2 min β 222ra
    223fr trace 22.00 min β 223ra
    α 219at
    category category: francium
    | references

    francium is a chemical element with the symbol fr and atomic number 87. prior to its discovery, it was referred to as eka-caesium. it is extremely radioactive; its most stable isotope, francium-223 (originally called actinium k after the natural decay chain it appears in), has a half-life of only 22 minutes. it is the second-most electropositive element, behind only caesium, and is the second rarest naturally occurring element (after astatine). the isotopes of francium decay quickly into astatine, radium, and radon. the electronic structure of a francium atom is [rn] 7s1, and so the element is classed as an alkali metal.

    bulk francium has never been viewed. because of the general appearance of the other elements in its periodic table column, it is assumed that francium would appear as a highly reactive metal, if enough could be collected together to be viewed as a bulk solid or liquid. obtaining such a sample is highly improbable, since the extreme heat of decay caused by its short half-life would immediately vaporize any viewable quantity of the element.

    francium was discovered by marguerite perey in france (from which the element takes its name) in 1939.[3] it was the last element first discovered in nature, rather than by synthesis.[note 1] outside the laboratory, francium is extremely rare, with trace amounts found in uranium and thorium ores, where the isotope francium-223 continually forms and decays. as little as 20–30 g (one ounce) exists at any given time throughout the earth's crust; the other isotopes (except for francium-221) are entirely synthetic. the largest amount produced in the laboratory was a cluster of more than 300,000 atoms.[4]

  • characteristics
  • isotopes
  • applications
  • history
  • occurrence
  • production
  • see also
  • notes
  • references
  • external links

Francium, 87Fr
Francium
Pronunciationm/ (FRAN-see-əm)
Mass number[223]
Francium in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
Cs

Fr

(Uue)
radonfranciumradium
Atomic number (Z)87
Groupgroup 1: H and alkali metals
Periodperiod 7
Blocks-block
Element category  Alkali metal
Electron configuration[Rn] 7s1
Electrons per shell2, 8, 18, 32, 18, 8, 1
Physical properties
Phase at STPsolid at 0 °C, liquid at r.t.
Melting point281.0 K ​(8.0 °C, ​46.4 °F) (estimated)[1]
Boiling point890 K ​(620 °C, ​1150 °F) (estimated)[1]
Density (near r.t.)2.48 g/cm3 (estimated)[1]
Vapor pressure (extrapolated)
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 404 454 519 608 738 946
Atomic properties
Oxidation states+1 (a strongly basic oxide)
ElectronegativityPauling scale: >0.79
Ionization energies
  • 1st: 393 kJ/mol[2]
Covalent radius260 pm (extrapolated)
Van der Waals radius348 pm (extrapolated)
Other properties
Natural occurrencefrom decay
Crystal structurebody-centered cubic (bcc)
Body-centered cubic crystal structure for francium

(extrapolated)
Thermal conductivity15 W/(m·K) (extrapolated)
Electrical resistivity3 µΩ·m (calculated)
Magnetic orderingParamagnetic
CAS Number7440-73-5
History
Namingafter France, homeland of the discoverer
Discovery and first isolationMarguerite Perey (1939)
Main isotopes of francium
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
212Fr syn 20.0 min β+ 212Rn
α 208At
221Fr trace 4.8 min α 217At
222Fr syn 14.2 min β 222Ra
223Fr trace 22.00 min β 223Ra
α 219At
Category Category: Francium
| references

Francium is a chemical element with the symbol Fr and atomic number 87. Prior to its discovery, it was referred to as eka-caesium. It is extremely radioactive; its most stable isotope, francium-223 (originally called actinium K after the natural decay chain it appears in), has a half-life of only 22 minutes. It is the second-most electropositive element, behind only caesium, and is the second rarest naturally occurring element (after astatine). The isotopes of francium decay quickly into astatine, radium, and radon. The electronic structure of a francium atom is [Rn] 7s1, and so the element is classed as an alkali metal.

Bulk francium has never been viewed. Because of the general appearance of the other elements in its periodic table column, it is assumed that francium would appear as a highly reactive metal, if enough could be collected together to be viewed as a bulk solid or liquid. Obtaining such a sample is highly improbable, since the extreme heat of decay caused by its short half-life would immediately vaporize any viewable quantity of the element.

Francium was discovered by Marguerite Perey in France (from which the element takes its name) in 1939.[3] It was the last element first discovered in nature, rather than by synthesis.[note 1] Outside the laboratory, francium is extremely rare, with trace amounts found in uranium and thorium ores, where the isotope francium-223 continually forms and decays. As little as 20–30 g (one ounce) exists at any given time throughout the Earth's crust; the other isotopes (except for francium-221) are entirely synthetic. The largest amount produced in the laboratory was a cluster of more than 300,000 atoms.[4]