Francium (Fr) is a group one alkaline metal. It has an atomic number of 87; meaning it has 87 protons and 87 electrons which are arranged in 7 different electron shells, the final shell containing just one electron. This means that francium could form a minus one ion in a oxidisation reaction as well as a less likely (almost certainly impossible) 7+ ion through an extensive reduction reaction. The mass number of francium is (on average) is 223, therefore one mole of francium would weigh 223. Ironically perhaps, there has never been enough francium to ever have a mole of it, the largest sample ever synthesised was 10,000 atoms, which isn’t even a large enough sample to weigh using even the most advanced instruments.
The other smaller, less reactive elements in Group 1 are hydrogen, lithium, sodium, potassium, rubidium and caesium. The two latter elements are have similar properties to francium and are probably the best elements to compare with, the in fact have to be stored with oils so that they do not react with water in what is usually a famously explosive reaction.
Because of the large amount of completed electron shells shielding the electron on the outer edge it is an extremely reactive element, and is actually the second rarest naturally occurring element on Earth (it is famously estimated that there is only about 20g in the Earth’s crust). It is found in uranium and thorium ores, due to the radioactive decay of the elements down to astatine and then down once again into francium. The element was discovered by a French physicist Marguerite Perey in 1939.
Francium is an extremely unstable element, having a half-life of only eight and a half minutes. Because of this extremely short time span in which to interact with francium it has been exceptionally hard to estimate the melting and boiling points, however using periodic trends down the group the melting point has been estimated at 22C and the boiling point at 660C.
Theoretically francium could form a single covalent bond with halogens such as fluorine and bromine, as well as forming various numbers of covalent bonds with non-metal elements from groups on the right side of the periodic table. However it is highly improbable that any compound could ever be formed using francium due to it’s instability.
Due, once again, to the extreme rarity of francium no practical application has ever been found; the benefits of using Francium as a treatment in cancer patients have been explored, but were deemed impractical only shortly after research began. This is partially due to the high costs of artificially synthesising Francium in nuclear reactions and then cooling it down enough so that is stable for longer periods of time.
