The search for more elements continues

By Hope Babowice

Kids Ink

You wanted to know

A young patron from the Vernon Area Library asked, "How many elements are there?"

Elements are the most basic form of a substance.

There are 118 elements, 90 that occur in nature and two more with isotopes found in nature. The rest are synthesized.

The nation's top scientists from the Heavy Elements Group at Lawrence Livermore National Laboratory linked with scientists from around the nation and Russia to coax six synthesized elements from their experiments.

"Lawrence Livermore National Laboratory has a mission of strengthening the United States' security by developing and applying world-class science, technology and engineering. We are looking for long-lived, super heavy elements because they might have some very interesting chemical or nuclear properties," Heavy Elements Group team member Dr. Mark Stoyer said.

Scientists developed a framework for elements, the periodic table, that categorizes elements in increasing order based on the number of protons. Each element is represented by a box with the name, atomic number (number of protons) and letter symbol.

Atomic numbers increase from left to right across rows, called periods. Groups, the vertical columns, are categorized by similarities.

Elements beyond 83 are unstable, and those beyond 104 are called super heavy elements (also known as SHE) because they have high numbers of protons. SHEs may only exist for fractions of a second; all of them were manufactured by scientists. The aim is to find the Island of Stability, a term that refers to synthesized elements that exist for a longer periods of time - seconds or minutes.

It could be that a SHE originated in nature, but because of a short half-life, the amount of time it takes for the atoms to decay, it no longer exists.

Stoyer explained that there's no certainty that all natural elements have yet been discovered.

"We don't know that all elements that exist in nature have been found. If the Island of Stability includes isotopes that are long-lived, say on the order of 10 percent of the age of the universe, then some should exist in nature," Stoyer said.

"If the Island of Stability only has isotopes that have half-lives of years, or even hundreds of years, then they all would have decayed away in the universe and wouldn't exist in nature. It would still be a great advance if we could make isotopes with such half-lives of a year because we could store them in a bottle and study them easily."

There's a long checklist needed when creating new elements. Specific atoms are targeted in a cyclotron at the Joint Institute for Nuclear Research Flerov Laboratory in Dubna, Russia, one of the collaborating research labs that works with Stoyer and his colleagues at the Heavy Element Group.

Just as challenging is measuring SHE, which are so short-lived. Results need to be verified. Add patience to the list. Stoyer said it took about 12 years to identify and confirm livermorium, named for the Lawrence Livermore National Laboratory.

"We run experiments for months at a time - 24 hours a day, seven days a week - in order to produce two to four atoms, which are identified in our separator and detector system. Once we observe something, then it takes time for another lab to reproduce the results.

"As an example, we created the first atom of element 116, livermorium, in 2000, but it wasn't confirmed until 2010 and named in 2012. Because the experiments are very difficult to do, there are only a few labs in the world performing this kind of research," Stoyer said.

Elements have variations called isotopes. These have the same number of protons but differing numbers of neutrons. For instance, carbon has six protons, but there are three carbon isotopes with different neutron configurations. Isotopes are not listed on the periodic table, but they offer a guide to scientists who work on synthesizing new elements.

The 118 elements on the periodic table comprise 3,000 isotopes. Scientific estimates forecast more than 4,000 undiscovered isotopes that could yield more boxes on the chart.

The payoff for this intense research is scientists are closer to understanding the complexities of atoms.

"The biggest discovery is that the Island of Stability exists. We are near to it," Stoyer said of the breakthrough. "These isotopes and elements would not exist except for the extra stability associated with quantum stabilization, the fact that certain configurations of protons and neutrons in the nucleus are very stable.

"We haven't landed on the center of the Island, more like on its beach at the shoreline, so the potential exists for even longer-lived isotopes that we haven't produced yet due to our limited beam and target combinations."

The periodic table continues to expand. Four more elements await confirmation by the International Union of Pure and Applied Chemistry.

Check it out

The Vernon Area Library suggests these titles on the periodic table and scientists whose discoveries have added to the science of chemistry:

• "Mendeleyev and the Periodic Table," by Katherine White

• "Chemistry: Investigate the Matter That Makes Up Your World," by Carla Mooney

• "Your Guide to the Periodic Table," by Gill Arbuthnott

• "The Basics of Chemistry," by Allan B. Cobb

• "The Basics of the Periodic Table," by Leon Gray