Bohrium (Bh). Diagram of the nuclear composition and electron configuration of an atom of bohrium-272 (atomic number: 107), an isotope of this radioactive element. The nucleus consists of 107 protons (red) and 165 neutrons (yellow). 107 electrons (white) bind to the nucleus, successively occupying available electron shells (rings). Bohrium, named after Niels Bohr and first synthesised in 1981, is a transactinide and transition metal in group 7, period 7, and the d-block of the periodic table. Bohrium-270 has a half-life of 61 seconds, its nucleus emitting an alpha particle to form dubnium-266.