Caesium has 40 known isotopes, ranging in mass number (i.e. number of nucleons in the nucleus) from 112 to 151. Several of these are synthesized from lighter elements by the slow neutron capture process (S-process) inside old stars[48] and by the R-process in supernova explosions.[49...
Atomic NumberElementNumber of electrons/outer shell 1Hydrogen1 3Lithium2,1 11Sodium2,8,1 19Potassium2,8,8,1 37Rubidium2,8,18,8,1 55Caesium2,8,18,18,8,1 87Francium2,8,18,32,18,8,1 All of the atoms in alkali metals have one electron in their outer electron shells. To become sta...