Ber·ze·li·us 
(bər-zēlē-əs, bĕr-sālē-s′), Baron Jöns Jakob 1779-1848.
(bər-zēlē-əs, bĕr-sālē-s′), Baron Jöns Jakob 1779-1848. Swedish chemist who published a table of atomic weights (1828); contributed to electrochemical theory; discovered cerium (1803), selenium (1817), and thorium (1828); and isolated silicon (1823).