1940 – USA
‘Elements heavier than uranium in the periodic table (transuranium elements) are made artificially. Uranium (U, atomic number 92) is the heaviest element known to exist naturally in detectable amounts on the Earth’
In 1933 ENRICO FERMI showed that the nucleus of most elements would absorb a neutron.
In 1940 McMillan, a nuclear physicist, produced and identified the first artificial element, neptunium (Np, 93). In 1943 Seaborg, a chemist, succeeded in creating plutonium (Pu, 94).
So far more than 20 synthetic elements have been created. All are unstable, decaying with half-lives ranging from a year to a few milliseconds.
At least thirteen transuranium elements have been named after scientists:-
curium (Cm, 96: Marie and Pierre Curie ), einsteinium (Es, 99: Albert Einstein ), fermium (Fm, 100: Enrico Fermi ), mendelevium (Md, 101: Dmitri Mendeleev ), nobelium (No, 102: Swedish chemist Alfred Nobel (1833-96), known for his bequest for the foundation of the Nobel Prizes ), lawrencium (Lr, 103: Ernest O. Lawrence, a physicist best known for development of the cyclotron ), rutherfordium (Rf, 104: Ernest Rutherford ), seaborgium (Sg, 106: Glenn Seaborg ), bohrium (Bh, 107: Niels Bohr ), meitnerium (Mt, 109: Lise Meitner ); roentgenium (Rg, 111: Wilhelm Conrad Röntgen was first created in 1994 by the GSI Helmholtz Centre for Heavy Ion Research near Darmstadt in Germany ), copernicium (Cn, 112: named after astronomer Nicolaus Copernicus ), flerovium (Fl, 114 named after Soviet physicist Georgy Flyorov ).