By Lynley Hargreaves 21/08/2015

Distinguished Professor Peter Schwerdtfeger
Distinguished Professor Peter Schwerdtfeger

Professor Peter Schwerdtfeger would like to find the end of the periodic table – where elements get heavier, more relativistic and much, much less stable.

The Massey University Professor is delivering the annual Rutherford Lecture series around New Zealand, and you can come along to find out more about why gold is yellow, what makes mercury liquid, and how understanding our chemical beginnings can help us look for alien worlds.

Livermorium, Ununoctium, Ununtrium, Ununpentium and Ununseptium have been discovered since the turn of the century. Aren’t we creating more super heavy elements than before?

No, the rate at which new elements are being added to the periodic table has actually been slowing down for the last 30 years. That’s because such experiments become increasingly more expensive and are difficult. Experimenters need to know the exact conditions required to produce each new element, and theoreticians have had to catch up. When you attempt to produce the next element up now, you’re missing more than a dozen neutrons to stabilize the nucleus. And you’re working with products that decay within a millisecond.

Why keep looking?

Chemists really like to know what is going on – and there is a lot still to learn about superheavy elements. Elements behave increasingly relativistically as they get heavier. They are also increasingly unstable, except that there may in theory be an island of stability where super heavy elements can exist naturally for longer periods, and that they may even exist naturally in small amounts.

Are there really super heavy elements hiding out there?

Probably not. The last naturally occurring element that we know of is uranium, with plutonium in trace amounts. But I know guys who have spent 10 years looking for superheavy elements in nature, looking in places like ice cores. Nobody has found anything. So maybe the theory is incorrect, and there isn’t an island of stability. Or, so some people say, if these elements were created in a supernova explosion they would have only lived for a few weeks, which means they vanished off the earth a very long time ago. I wouldn’t say it was this quickly – I would bet that we won’t find them, but that some isotopes may have existed naturally for millions of years.

How can heavy elements help us look for life on other planets?

We still have to fill in the details about the synthesis of the elements in our universe, galaxies and stellar environments. It is clear that carbon and oxygen, for example, must be produced and subsequently accumulated on our planet earth. That is we need the right conditions for this to happen. Once we have a more complete picture we can better understand the formation of other planets in other solar systems sustaining other life forms.

How will you find the end of the periodic table?

I’m really curious where the periodic table really ends. It may be that we cannot create elements beyond 119 or 120. But we can still simulate these on computers using quantum theory. There is speculation – though it is sheer speculation – that the Periodic Table has to finish at around 170 protons.

The 2015 Rutherford Lecture: Going Super Heavy will be given in Hamilton, Palmerston North, Wellington, Christchurch, Dunedin and Auckland.

These interviews are supported by the Royal Society of New Zealand, which promotes, invests in and celebrates excellence in people and ideas, for the benefit of all New Zealanders.