## Wednesday, April 07, 2010

### Dubna: ununseptium 117 discovered

Various media report that a new element was created in JINR, Dubna, Russia: it's called ununseptium which means one-one-seven-ium in Latin. ;-)

Another element with Z=118, ununoctium, had actually been already created some time ago so they were filling a gap.

The 117th element was created by fusion of Ca(48) and Bk(249). An excited isotope of the new element, Uus(297), decayed either to Uus(294) - with half-life of 78 ms - and 3 neutrons or Uus(293) - with half-life of 14 ms - and 4 neutrons.

You might think that such heavy elements have to belong among the transuranium elements - the assorted radioactive junk. But technically speaking, you would be wrong. Because of 7 electrons in the outer shell of a hypothetical atom, the 117th element would actually be a halogen, together with fluorine, chlorine, bromine, iodine, and astatine. (In Czech, we use the same names with the awkward "ine" omitted.)

However, the eka-astatine, as the 117th element can also be called, is unlikely to be too useful in chemistry due to its tiny lifetime. The instability of the nuclei is what gradually makes the Mendeleev periodic table less useful for high values of Z. Well, it's not just the table itself: the heavy elements themselves are probably getting less useful unless you invent some really creative - and really fast - application of them.

A better name may be absent for many years: the currently highest-Z nicely named element, the 112-ium, got its sensible name, Copernicium, one decade after its discovery.

Thanks to Olda K.