Researchers have rewritten one of the basic building blocks of science: the periodic table of elements.

A group of chemists have officially altered the atomic weight of 10 elements on the table -- a list of the 118 basic atoms that hangs on the wall of almost every high school science classroom in the world.

"Keeping track of elements is really exciting work," says Michael Wieser, a professor of chemistry at the University of Calgary and a member of the international group that rewrote the table. "These changes aren't just of interest to chemists or people who specialize in these very, very tiny weight differences: there's real information in there with real applications."

"It's fascinating stuff … we can use this in physics, geology, archeology -- there are limitless possibilities."

The committee, informally known as the International Union of Pure and Applied Chemistry's Commission on Isotopic Abundances and Weights, rearranged the squares that make up the periodic table to reflect new and more accurate information about the atomic weight of 10 elements.

An atomic weight refers to the ratio of an element's average mass per atom to one twelfth of the mass of a single atom of carbon-12.

Instead of giving them a hard-and-fast atomic weight -- calculated based on the number of isotopes of any given element -- the committee instead gave them a range, reflecting minute differences in the weight of slightly different versions of each element.

"Our ability to measure these very, very tiny differences has really improved," Wieser said in an interview with CTV.ca. "And I'm sure we're going to see even more variations in the future."

For example, the element boron has an atomic weight of between 10 or 11 and in the past was listed at 10.811 -- an average of the weight of boron isotopes found in nature.

The new table will reflect the fact that boron can have an atomic weight ranging from 10.806 to 10.821, depending on where in the world the element originates.

The new table, outlined in the journal Pure and Applied Chemistry, will now list ranges for boron, hydrogen, lithium, carbon, nitrogen, oxygen, silicon, sulphur, chlorine and thallium.

And Wieser says that the next revisions to the periodic table, due in two years, will likely include more accurate weight ranges for another 10 elements, including helium, nickel, copper, zinc and lead.

"People didn't expect to see variations in some of these elements, but we did," he said. "And the result is fascinating."

Precise measurement of isotopic ratios can be used to determine the purity and source of all kinds of chemicals, from the metal used in coinage to food.

The technique has been used to catch unscrupulous merchants trying to pass off cheap Indonesian or Chinese honey as high-grade New Zealand honey, based on a super-accurate measurement of the carbon isotopes in the honey to identify its origin.

Wieser said it can help with everything from detecting athletes who use performance-enhancing drugs to tracking pollution.

"You can tell from the atomic weight of the testosterone – or the carbon in the testosterone molecules – in the body whether it's artificial or naturally produced," he said. "Looking at isotopes of oxygen or sulfur lets you track pollutants in the air or water right back to the source."

The periodic table has been edited in the past to account for the discovery of new elements. When it was first devised 140 years ago by Russian chemist Dmitri Mendeleev, only 63 elements were listed. Now there are 118 and scientists are always searching for more.

Weiser, the secretary of the committee, joked that he is the one who is literally rewriting the periodic table. "But it's very much a group effort by all 20 of us on the committee."

And changing something as fundamental as a table of elements can be controversial in the conservative world of chemistry, but Weiser says the committee is only reflecting what happens in the real world.

"People are probably comfortable with having a single value for the atomic weight, but that is not the reality for our natural world," he said.

"My hope is that some student somewhere will look up at this new table and see the variation and say: ‘Why is that?'"