American and Russian teams have "created" the heaviest element till now, known as 118. The last naturally occurring element was found in 1925, but since then the scientists looked for creation of new heavier artificial elements.

Scientists at the Lawrence Livermore National Laboratory in California and the Joint Institute for Nuclear Research in Dubna, Russia, have bombarded californium-249 atoms with calcium-48 ions to create the 118 element, with a total atomic mass of 294 units. The existence of this element was determined by atomic decay patterns observed at the JINR U400 cyclotron. The alpha decay particles were detected from element 118 to element 116 and then to element 114 and from 114 to 112. The alpha particles are nuclear fragments made of two protons and two neutrons.

The same decaying pattern was observed for element 116 in earlier experiments. Till now, the Russian-American team has discovered five new elements (113, 114, 115, 116 and 118). The 118 element was detected from three atoms: the first atom was found in 2002 and another two atoms in 2005. Because the lifetime for the three atoms was 0.9 ms, scientists could not perform any kind of chemical tests, which needs at least an hour's time.

Element 118 enters the category of noble gases, laying right below radon on the periodic table of elements. "The decay properties of all the isotopes that we have made so far paint the picture of a large, sort of flat 'Island of Stability' and indicate that we may have luck if we try to go even heavier," said Ken Moody, Livermore's team leader.

The "Island of Stability" refers to the possibility of elements which have stable "magic numbers" of protons and neutrons. It means that certain isotopes of some transuranic elements (elements with atomic numbers greater than 92) might be far more stable, with a bigger lifetime.

The team plans to "create" the element 120 by bombarding plutonium atoms with iron ions. "The heavy element community will continue to search for new elements until the limit of nuclear stability is found," said Mark Stoyer of LLNL.