The periodic table?s familiar flatland may soon become a three-dimensional landscape reflecting these evolving faces of matter, writes Prakash Chandra.india Updated: Nov 06, 2006 01:42 IST
Now you see it, now you don’t! Element 118, the heaviest chemical element known, exists in the lab for less than a thousandth of a second. Scientists from the Lawrence Livermore National Laboratory, California, and their Russian partners at the Dubna Nuclear Research Centre, Moscow, recently identified it by bombarding californium (element 98) with calcium (element 20) atoms.
Most of the calcium ions flew right through the californium, missing its nuclei. But a few hit smack on, fusing the two nuclei to form — fleetingly — element 118, before the phantom nuclei broke down into smaller, more stable atoms of elements 116 and 114.
This could dramatically transform one of science’s most visible icons: the periodic table. More than 130 years after Russian chemist Dimitri Ivanovich Mendeleev arranged elements in rows, based on their atomic weights (the number of protons and neutrons in an atom’s nucleus), the table remains essentially unchanged. In the original, the 63 known elements were in columns, based on the number of chemical bonds an atom forms. Subsequently, they were placed according to atomic numbers (the number of protons).
The higher an element’s position on the table, the more protons and neutrons — and more mass — its atomic nucleus has. The lightest, hydrogen, has only one proton, making it number 1, while uranium, with 92 protons, is the heaviest natural element.
Using the table, an element’s chemical behaviour can be altered by adding or removing atoms. Want to turn lead (atomic number 82) into gold (atomic number 79)? Simple — just remove three protons.
So where do you put element 118, which exists for milliseconds, on Mendeleev’s classic layout? The table was last altered in the Forties, when US chemist Glenn Seaborg created a separate group for the rare earth and radioactive elements.
And there’s something even more alien: superatoms, or clusters of atoms of an element that take on the properties of other elements.
The periodic table’s familiar flatland may soon become a three-dimensional landscape reflecting these evolving faces of matter.