1. 98Californio CaliforniumMass: 15,10 u1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p67s25f10Melting point: 1173 KBoiling point: 1743 KDensity: 15,1 g/cm3Discovery: 1950Californium is a radioactivemetallic chemical element. The element was first made at the Universityof California, Berkeley in 1950 by bombarding curium with alpha particles(helium -4 ions). Its an actinide element, the sixth transuranium elementto be synthesized, and has the second-highest atomic mass of all theelements that have been produced in amounts large enough to see withthe unaided eye. Its the heaviest element to occur naturally on Earth;heavier elements can only be produced by synthesis.