Periodic table gets bit bigger

Remember the periodic table from high school chemistry? It just got a little bigger.

Two new chemical elements, numbers 114 and 116, have been officially recognised by an international committee of chemists and physicists.

The elements last for less than a second and join such familiar neighbours as carbon, gold, tin and zinc. The new ones don't have approved names yet.

That brings the total of known elements to just 114 because elements 113 and 115 haven't been officially accepted yet, said Paul Karol of Carnegie Mellon University.

He chaired the committee that recognised the new elements, based on experiments done in 2004 and 2006 by a collaboration of scientists from Russia and the Lawrence Livermore National Laboratory in California.

Over the past 250 years, new elements have been added about once every 2.5 years on average, Karol said.

The committee announced its decision last week.