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.
- ‘The graph above which identifies francium by its radiation is from the notebook of the discoverer, Margurerite Perey, an assistant to Marie Curie.’
- ‘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.’
- ‘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.’
- ‘As a result, lithium has the smallest atomic radius and francium has the largest.’
- ‘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.’
- ‘Along the way, these disintegration series produce radioactive isotopes of protactinium, thorium, actinium, radium, francium, radon, astatine, polonium, bismuth, lead, thallium and mercury.’
- ‘Due to its extremely short half-life, there's no reason for considering the effects of francium in the environment.’
- ‘The francium that does exist is found in trace amounts in uranium ores.’
- ‘All isotopes of francium are radioactive, with francium - 223 being the most stable with a half life of 22 minutes.’
- ‘It means the hydroxides of the alkali metals: lithium, sodium, potassium, rubidium, cesium, and francium.’
- ‘There is much less than an ounce of francium at any given time in the whole Earth.’
1940s: from France (the discoverer's native country) + -ium.