In search of the heaviest element

11 August 2015

In search of the heaviest element

Like absolute zero on the temperature scale, what is the heaviest element that could possibly exist? That’s the question 2015 Rutherford LecturerDistinguished Professor Peter Schwerdtfeger would love to know the answer to.

Director of the Centre of Theoretical Chemistry and Physics at Massey University, Albany, his diverse research interests of theoretical chemistry and physics, computer science and mathematics allow him to probe the subject of ‘super heavies’ – the elements at the bottom of the periodic table with a nuclear charge of 118 or higher. But how high can they go?

“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,” Professor Schwerdtfeger says.

The heaviest elements that are known to occur naturally are uranium (atomic number 92), with plutonium in trace amounts. Heavier elements are increasingly unstable, decaying almost instantly, although there has been some speculation that there may be an ‘island of stability’ where super heavy elements can exist for longer periods.

Are there some super heavy elements lurking under rocks or trapped in ice somewhere? Professor Schwerdtfeger thinks this is highly unlikely. “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.”

The lack of naturally occurring super heavy elements means that in order to study them, scientists have to first make them, and this is problematic. “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.”

Even so, the super heavy elements of Livermorium, Ununoctium, Ununtrium, Ununpentium and Ununseptium have been made in recent years and the quest to make heavier elements continues.

Once we understand the fundamentals about how progressively heavier elements are generated in the universe, it may help us search for life outside Earth, according to Professor Schwerdtfeger. “It is clear that for life to exist on planet Earth, carbon and oxygen, for example, must be produced and subsequently accumulated and 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 and whether they can sustain other life forms.”

Distinguished Professor Schwerdtfeger was awarded the 2014 Rutherford Medal, the Royal Society of New Zealand’s top research medal, for his world-leading contribution to fundamental aspects of chemical and physical phenomena in atoms, molecules and condensed matter. He will give the 2015 Rutherford Lecture in Hamilton, Palmerston North, Wellington, Christchurch, Dunedin and Auckland from 11 August – 7 October 2015. Tickets are free and can be reserved at www.royalsociety.org.nz/events.

Venue details:

• HAMILTON | 7.30pm Tuesday 11 August| Gallagher Concert Chamber, Academy of Performing Arts, University of Waikato (entry via Gate 2B on Knighton Road)| Hamilton tickets

• PALMERSTON NORTH | 7pm Thursday 13 August| Speirs Centre, Palmerston North Boys High School, Featherston Street | Palmerston North tickets

• WELLINGTON | 6pm Tuesday 18 August | Aronui Lecture Theatre, Te Whare Aparangi, 11 Turnbull Street, Thorndon | SOLD OUT

• WELLINGTON | 6pm Wednesday 19 August | Aronui Lecture Theatre, Te Whare Aparangi, 11 Turnbull Street, Thorndon | Wellington tickets

• CHRISTCHURCH | 6pm Wednesday 26 August | C1 Central Lecture Theatre, Arts Road, University of Canterbury | Christchurch tickets

• DUNEDIN | 6pm Thursday 27 August | Hutton Theatre, Otago Museum, Great King Street | Dunedin tickets

• AUCKLAND | 6pm Wednesday 7 October | Auditorium, Level 2, Auckland Museum, The Domain, Parnell | Auckland tickets (overflow-room available)

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