The periodic table is a cornerstone of chemistry and science, a chart that organizes all known elements in the universe. But how many elements are actually on this table, and how did we come to know them all? The answer isn’t as static as you might think.
Currently, the periodic table officially hosts 118 elements. These elements are arranged in order of increasing atomic number, which is the number of protons in the nucleus of an atom. This number defines what element it is. You might think of this as the element’s unique ID.
But the story of the periodic table and the elements it contains is one of ongoing discovery and refinement. For a long time, there were gaps in the periodic table, spaces for elements that scientists predicted existed but hadn’t yet been found or created.
One such gap was element 43, technetium. Berkeley Lab played a pivotal role in filling this gap. In 1937, Emilio Segrè, who had previously worked at Berkeley Lab, realized that molybdenum, element 42, bombarded with deuterium in the cyclotron, could potentially transform into element 43. He requested a piece of molybdenum that had been exposed at the Rad Lab from Ernest Lawrence.
As physicist Robert Cahn from Berkeley Lab explains, “Segrè knew that by bombarding molybdenum, element 42, with deuterium, the deuterium could increase the size of that nucleus until it was 43 by adding a proton. So he realized it might be possible to find that missing element number 43 … by doing a chemical separation.” This ingenious approach led to the discovery of technetium, the first element to be artificially produced, filling a long-standing void in the periodic table.
The discoveries didn’t stop there. During the era of groundbreaking nuclear research, Berkeley Lab scientists were at the forefront of discovering even more elements, particularly those heavier than uranium (element 92), which was the heaviest naturally occurring element known at the time. Glenn Seaborg, a prominent figure at Berkeley Lab, even famously announced the discovery of two new elements, americium (element 95) and curium (element 96), on a children’s radio show in 1945. This playful announcement highlighted the rapid pace of discovery at the time, where neptunium (element 93) and plutonium (element 94) had also been discovered in quick succession.
Beyond discovering new elements, Berkeley Lab has also been instrumental in the study of isotopes. Isotopes are variations of elements that have the same number of protons but different numbers of neutrons. Berkeley Lab boasts credit for discovering over 630 isotopes, more than any other institution globally. These isotopes have proven invaluable in various fields, most notably in medicine. Radioisotopes, pioneered in part by Berkeley Lab, are now essential tools for diagnosing and treating diseases, marking a significant contribution to nuclear medicine.
Current research at Berkeley Lab continues to push the boundaries of the periodic table. Scientists are intensely studying superheavy elements, those at the very end of the table like moscovium (element 115) and rutherfordium (element 104). They are developing advanced techniques to precisely measure the properties of these artificially created elements, aiming to refine our understanding of nuclear physics and potentially uncover unforeseen applications. As Barbara Jacak, director of Berkeley Lab’s Nuclear Science Division, points out, the initial discoveries of synthetic elements had unforeseen impacts, leading to applications like radioisotopes in cancer treatment. The ongoing research into superheavy elements holds similar potential for future breakthroughs we can only begin to imagine.
In conclusion, the periodic table currently lists 118 elements, a testament to centuries of scientific inquiry and discovery. Organizations like Berkeley Lab have been central to expanding our knowledge of these fundamental building blocks of matter, both by discovering new elements and by unlocking the potential of isotopes. The quest to understand the elements and potentially expand the periodic table further is an ongoing endeavor, promising exciting scientific advancements in the years to come.
