Super heavy element
All the elements that appear in the periodic table beyond Uranium (whose atomic number is 92) have an ephemeral existence before they disintegrate. These superheavy elements known as "transuranic elements" are radioactive and have a half-life shorter than the age of the Earth, which means that they are no longer found on our planet or in the Solar System if they ever were. In fact (with a few exceptions), the higher the atomic number, the shorter the half-life of an element.
The Glenn T. Seaborg Nobel Prize in Chemistry went so far as to empirically study the half-life of transuranium elements as to predict in 1991 an "island of stability", in other words, a "magical" number of protons and neutrons capable of giving stability to a possible superheavy element. The key, according to Seaborg, is that the nucleus of the atom is as spherical as possible, something that can happen with 298 nucleons (protons plus neutrons).
Currently, two isotopes of Ununpentio, 287Uup and 288Uup, have been synthesized. The half-life of both was just a few milliseconds, but 299Uup is expected to be the first super heavy stable element, as it contains the "magic" number of 184 neutrons.
It is difficult to anticipate what practical uses could be obtained by researching the new superheavy elements. For now, the focus is on its discovery and not on its applications. However, some elements synthesized in the past have brought enormous benefits to the population. For example, the element 95, known as Americium (discovered in 1944) is used in the medical and radiographic industry.
Star fuel?
Although element 115 was discovered in 2004, it was actually mentioned a few years earlier by a rather controversial character. Robert Scott Lazar (b. 1959) broke into several media outlets in late 1989 telling a rather unlikely story. Lazar claimed to have worked for the U.S. government as a physicist at the famous Area 51 secret military base in Groom Lake, Nevada. His job was to reverse engineer aircraft captured by the Americans, especially their propulsion system. Although Lazar first thought that they were state-of-the-art secret aircraft, he ended up concluding that they were not of ground origin.
This story would not be much more interesting if it were not for what Lazar commented in 1989 (15 years before the discovery of Ununpentio) about his findings on the propulsion system. According to Lazar, the fuel for the alien ships was element 115 in a stable form. It provided an energy source which produces anti gravitational effects under a continuous bombardment of protons, together with antimatter to achieve a high energy production.
As the strong nuclear field of interaction of the nucleus of element 115 is properly amplified, the resulting large-scale gravitational effect would be a distortion or deformation of space-time that would serve for long stellar journeys.
Although Lazar's story may be pure fantasy, it is still interesting to try to imagine the possible applications of element 115.