berkelium ber·ke·li·um (bər-kē'lē-əm, bûrk'lē-əm)
A synthetic radioactive element. Its most stable isotope, Bk 247, has a half-life of 1,380 years. Atomic number 97; melting point 1,050°C; valence 3, 4.
A synthetic, radioactive metallic element of the actinide series that is produced from americium, curium, or plutonium. Its most stable isotope has a half-life of about 1,400 years. Atomic number 97; melting point 986°C; valence 3, 4. See Periodic Table.