Upstream | June 11, 2009 | 45 comments

Periodic table gets a new element

source: http://news.bbc.co.uk/2/hi/science/nature/8093374.stm

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The ubiquitous periodic table will soon have a new addition - the "super-heavy" element 112.

More than a decade after experiments first produced a single atom of the element, a team of German scientists has been credited with its discovery.

The team, led by Sigurd Hofmann at the Centre for Heavy Ion Research, must propose a name for their find, before it can be formally added to the table.

Scientists continue the race to discover more super-heavy elements.

Professor Hofmann began his quest to add to the periodic table in 1976.

The fusion experiments he and his colleagues carried out at the centre have already revealed the existence of elements with atomic numbers 107-111.

These are known as "super-heavy elements" - their numbers represent the number of protons which, together with neutrons, give the atom the vast majority of its mass.

To create element 112, Professor Hofmann's team used a 120m-long particle accelerator to fire a beam of charged zinc atoms (or zinc ions) at lead atoms. Nuclei of the two elements merged, or fused, to form the nucleus of the new element.

These very large and heavy nuclei are also very unstable. They begin to fall apart or "decay" very soon after being formed - within a few milliseconds, in this case.

This releases energy, which scientists can measure to find out the size of the decaying nucleus.

But such experiments produce very few successful fusions, and scientists need increasingly powerful accelerators to run experiments for longer and find the elusive, unstable elements.

This is why it took such a long time for element 112 to be officially recognised by the International Union of Pure and Applied Chemistry (IUPAC).

Its discovery had to be independently verified, and so far only four atoms have ever been observed.

IUPAC temporarily named the element ununbium, as "ununbi" is derived from the figures "one one two" in Latin; but Professor Hofmann's team now has the task of proposing its official name.

He is currently keeping the shortlist under wraps.

http://www.periodicspiral.com/
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