Four New Elements Complete Seventh Row of Periodic Table

By Mike Howie

Four new elements have been added to the periodic table, finally completing the seventh row. The last time anything was added to the table was 2011, when elements 114 and 116 were discovered.

All four of the new elements are manmade and superheavy. They were synthesized by colliding nuclei into each other and tracking their decay. The atomic numbers for the new elements are 113, 115, 117 and 118. They don’t have names yet, however, so they are going by the working titles ununtrium (Uut), ununpentium (Uup), ununseptium (Uus) and ununoctium (Uuo), respectively. The discoverers of the elements will create permanent names and symbols for the elements in the coming months.

The discoveries were made by scientists spread across the globe. Element 113 was discovered by scientists led by Kosuke Morita at RIKEN in Wako, Japan. It’s a proud moment for Morita and his team as this is the first time an element was discovered and will be named in Asia. The other three elements, 115, 117 and 118, were discovered by scientists from the Joint Institute for Nuclear Research working in Dubna, Russia, the Lawrence Livermore National Laboratory in Livermore, California, and the Oak Ridge National Laboratory in Oak Ridge, Tennessee, respectively.

The fact that all four of these elements are superheavy means they decay rapidly, which made them difficult to find. However, they continue the trend of newer superheavy elements with slightly longer lifespans, which gives scientists hope that they may find the “island of stability,” a group of stable superheavy elements, which could possibly be somewhere around elements 120 or 126.

All four elements are radioactive, and not much else is known about them. Both elements 113 and 115 are classified as metals and are expected to be solid at room temperature. Element 117, a member of the halogen group, is expected to be solid, but its classification is unknown. Element 118, a member of the noble gas group, is expected to be a gas and is classified as a non-metal.

Says Who?

Just because a scientist or group of scientists say they’ve discovered a new element doesn’t mean it’s true.

That’s where the International Union of Pure and Applied Chemistry, or IUPAC for short, steps in. IUPAC is an international, non-governmental objective body that oversees the periodic table. They’re the ones who determine the validity that a new element has been discovered and decide who has the right to name the new element. They occasionally mediate disputes as to who discovered a new element, which happened with element 113 when both RIKEN and the Russian-American team that discovered elements 115, 117 and 118 both claimed discovery.

The new-element process, as far as IUPAC is concerned, is fairly simple. After scientists have done the work of smashing different elements into each other, they publish their claim in scientific literature. IUPAC then analyzes the claim, determining if the experiments were valid and if it meets the criteria for a new element as well as who deserves credit for the discovery. They then publish their analysis in their official journal, Pure and Applied Chemistry. At this point the element gets a provisional name, which is based on its atomic number, and a square on the periodic table. The credited discoverers then submit a name — which must relate to mythological concepts, minerals, places, countries, properties or scientists — and symbol for the new element to IUPAC. The proposed name and symbol are then publicly reviewed by neutral scientists before IUPAC makes its decision. Finally, IUPAC publishes the name and symbol in their journal and adds it to the periodic table.

What’s the Point?

These elements, at this point in time, exist in the most generous of terms. Each lives for far less than a second before it decays into lighter elements. For most of us, that’s so little time it’s useless. But it is enough time for scientists to learn some things.

Just because these elements hardly exist on Earth doesn’t mean they can’t have easier lives somewhere else in the universe. It’s believed that heavy atoms like those found in these four new elements are created during star death, so recreating them here can give us insight into that process. And the fact that they’re radioactive and decay so quickly could help us learn more about the general process of radioactive decay, something that would be immensely helpful in learning how to deal with radioactive waste and about the potential future of our energy supply.

Even if these and other superheavy elements aren’t useful on our planet, they help us learn more about our universe. Creating and studying them is, at the very worst, knowledge for the sake of knowledge, which is one of the many goals of science.

What’s Next?

The obvious answer to this is, of course, the eighth period of the periodic table, starting with elements 119 and 120. But finding these elements isn’t as simple as moving from one project to the next.

The heavier these elements get the harder they are to synthesize. To understand why that is, you need to know a little about the synthesizing process itself. Scientists use a heavy element as a target and then slam lighter elements into it at high speeds. The elements chosen for the tests depend on the number of protons they have. The idea behind this is that when the elements collide they will merge into a single element with the sum of those protons. For example, iron, which has 26 protons, would be collided into plutonium, which has 94 protons, in an attempt to make element 120 (atomic numbers are based on the number of protons in an element).

This method worked well in the past, but it’s unlikely that it will continue to work well with heavier elements. To create a heavier element more projectiles would need to be collided into the target, but that would burn the target and could also burn the detector. It’s true that a larger target could be used, but that’s difficult and takes time. It took two years to make the target that was used to produce element 117.

So to keep discovering more elements, scientists need more advanced equipment, which is a long process in itself. Progress will happen – once upon a time nobody thought anybody would get this far – but it will take time.

Beyond the limits of technology, there are some physical limits on how many elements there could possibly be. As atomic nuclei get larger, the electrons that circle them have to move faster. That means at some point electrons will have to move faster than the speed of light for certain elements to exist. But it’s physically impossible for anything to go faster than the speed of light, so there must be some limit to how big a nucleus can be, and hence a limit to how many elements there can be. Physicist Richard Feynman predicted that element 137 would be the limit, but other calculations predict that it will be around element 170.

Those potential limits leave us with a lot of elements to discover, and a lot more work for the scientific community.