The periodic table lists the elements in terms of their atomic weight. This is a measure of how many protons are present in the nucleus of each atom. The lightest of all is hydrogen; the heaviest at the other end of the table is unoctium. But of course, nothing is ever as simple as it seems. In addition, the elements in the table are also classed into groups which exhibit similar characteristics. However, this article is not about the general elements in the table, but the theoretical ones that exist beyond the periodic table we currently have.
At the highest or heaviest end of the table, we have what are termed the superheavy elements. They begin at number 105 and end with unoctium at 118. However, these are not stable and are radioactive. They do not appear, as far as we know in nature but have only been created in the laboratory.
However, it is thought that using theoretical and mathematical work, a form of stability might be possible at atomic weights in excess of what we have now. This would mean that they would be extremely dense. In order to give us an idea of this, the heaviest stable naturally occurring element is the metal osmium. It occupies number 76 in the table and it has a density of 22.59 grammes per cubic centimetre. This may not sound a lot but it is almost twice the density of the Earth’s core and almost as dense as the core of the giant planet Jupiter. Believe me, that is pretty dense.
The question remains, is there any evidence that any of these very superheavy elements could actually exist? The exciting answer is that there very well could be. It will not be easy to confirm but we are already beginning to explore where they may exist. In essence, we are talking about asteroids. We have already visited some asteroids and even brought some material back to Earth for analysis. This was from the asteroid Bennu.
However, many other asteroids are being investigated remotely by probes and from observations on Earth. One in particular is of major interest (although there are several that we really would like to explore). It is the asteroid 33 Polyhymnia. It is approximately 36 miles across. Initial measurements came back with a density of 75.28 grammes per cubic centimetre. This is unbelievable and that is the opinion of most scientists; that the measurement must be wrong.
However, a team at the University of Arizona decided to use a theoretical model to investigate whether the possibility of such elements could exist. Although imprecise, they did find that it was theoretically possible for there to be a region of stability around atomic number 164. In addition, it showed that if true, then it could give a density range of between 36 and 68.4 grammes per cubic centimetre.
Yes, this is all hypothetical and it may take many years to prove it to be true or false. But, here is literally a leap in the darkness of space. Such theoretical elements have been termed Compact Ultra Dense Objects or CUDOs. We know there is not enough mass in the universe to explain how the universe operates and this hidden matter has been called Dark Matter. We believe it has to exist but we cannot detect it. So, if these superheavy asteroids and other objects in the universe do exist, then it could give us the additional missing mass and solve the problem of Dark Matter. At the present time, these elements are not only beyond the periodic table but also beyond our knowledge.
John Pullen 