noun

• The chemical element of atomic number 87, a radioactive member of the alkali metal group. Francium occurs naturally as a decay product in uranium and thorium ores.

  ‘Along the way, these disintegration series produce radioactive isotopes of protactinium, thorium, actinium, radium, francium, radon, astatine, polonium, bismuth, lead, thallium and mercury.’

  More example sentences

  • ‘Along the road to bismuth, a number of extremely high energy or otherwise dangerous alpha emitters will be present in the sample in small quantities: radium, actinium, thorium, francium, pollonium and radioactive lead, among others.’
  • ‘These elements - lithium, sodium, potassium, rubidium, cesium and francium - all react with water to give solutions that change the color of a vegetable dye from red to blue.’
  • ‘It means the hydroxides of the alkali metals: lithium, sodium, potassium, rubidium, cesium, and francium.’
  • ‘All isotopes of francium are radioactive, with francium - 223 being the most stable with a half life of 22 minutes.’
  • ‘As a result, lithium has the smallest atomic radius and francium has the largest.’
  • ‘Due to its extremely short half-life, there's no reason for considering the effects of francium in the environment.’
  • ‘There is much less than an ounce of francium at any given time in the whole Earth.’
  • ‘This is the only isotope of francium occurring in nature, but at most there is only 20-30 g of the element present in the earth's crust at any one time.’
  • ‘The graph above which identifies francium by its radiation is from the notebook of the discoverer, Margurerite Perey, an assistant to Marie Curie.’
  • ‘The francium that does exist is found in trace amounts in uranium ores.’