There are four new seats at chemistry’s venerable periodic table, added by international judges for work performed by scientists at Lawrence Livermore National Laboratory and in Japan and Russia.

With the addition of these elements — numbered 113, 115, 117 and 118 — the awkward seventh row of the table is now complete, creating a neatly squared corner and making millions of textbooks instantly obsolete.

The new elements lead brief lives, surviving only a millisecond or so. They’re extraordinarily rare; fewer than 10 atoms of each have been created. And they offer no practical benefit to society.

But their creation helps answer this profound question: What are the extreme limits to the size of matter?

“They help us understand how the physics of matter works,” said scientist Dawn Shaughnessy of Lawrence Livermore, who led the lab’s collaboration with Russian scientists on elements 115, 117 and 118. “Every time a new element is made, it changes our ideas about how the nucleus is held together.

“As we keep pushing further and further,” she added, “we learn that the particles inside the nucleus of the atoms want to be organized in a specific way.”

The four elements — produced between 2004 and 2010 — were verified Wednesday by the International Union of Pure and Applied Chemistry, the gatekeeper of the periodic table, which offers a simple and elegant organizing principle for the science of chemistry.

“The chemistry community is eager to see its most cherished table finally being completed down to the seventh row,” Jan Reedijk, president of the Inorganic Chemistry Division of the IUPAC, said in a statement. The newcomers are considered “superheavy” elements, because they have so many protons in each nucleus. This makes them much larger, heavier and more complicated than familiar elements such as oxygen, hydrogen or carbon. Each element is made by fusing together two lighter elements. Scientists bombard a target in a particle accelerator. In the collision, the projectile and target atoms fuse together to form gigantic atoms. The new element embeds itself in a detector and radiates energy ever so briefly before disappearing.

For elements 115, 117 and 118, scientists at Russia’s Joint Institute for Nuclear Research in Dubna ran the accelerator and performed the experiments.

It was the responsibility of Shaughnessy’s Livermore team, using powerful supercomputers, to analyze the data emailed from Russia. The data document the energy of each element’s creation and decay process.

“It is exciting to be recognized for our efforts,” said Shaughnessy, the group leader for experimental nuclear and radiochemistry at Livermore Lab. “You do these experiments and they take many months. Finally, years later, you have an international body recognizing your work.”

Ever since UC Berkeley scientists found a way to artificially create elements in 1974, Livermore Lab has produced many new elements. Each is heavier and lives a briefer life than the one before it.

They delight in adding new names, even as the rest of us struggle with old ones. These include berkelium (element 97), californium (98) and lawrencium (103), named after Ernest O. Lawrence, the physicist for whom the Lawrence Livermore National Laboratory is named. The element livermorium (116) honors the lab and the city of Livermore.

The new additions still await names and symbols. For now, they’ll use Latin-based placeholder names, such as “ununpentium,” aka Uup, element 115. Once named, they will force the redesign of textbooks and wall charts all over the world.

The table may continue to grow, as technology improves, physicists say.

Yet it is approaching the end, said Shaughnessy.

“At some point, there will be a limit,” she said. “There will be a physical limit to our ability to perform experiments — our electronics will not be fast enough to detect them. And there will be a scientific limit to what a nucleus can do. It may get so huge, with so many protons, that it can’t exist without being torn apart.

“But we don’t think we’re quite there yet,” she added brightly.

Contact Lisa M. Krieger at 650-492-4098. Follow her at Twitter.com/LisaMKrieger and Facebook.com/Lisa M. Krieger.