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By Laura Cooper on

Model Scientists: Playing with Molecular Structures

Volunteer Laura Cooper explains the science behind a popular activity in our Wonder Materials: Graphene and Beyond exhibition.

As a volunteer in the Wonder Materials: Graphene and Beyond exhibition, I have spent many afternoons in The Hive area (seen below) running what I call the “Buckyball School”. Here, I show children and their parents how to become model scientists, and use magnetic hexagons and smaller pentagons to construct a football-shaped structure (also known as a truncated icosahedron).

 

Picture of The Hive area in the Wonder Materials: Graphene and Beyond exhibition at the Museum of Science and Industry, Manchester

 

They begin with a middle hexagon flat on the table, and then add alternating hexagons and pentagons around its edges until each side is covered. Then, they simply lift these outer shapes up and click the sides together to form a 3D base. From this, most children immediately get the concept, and continue adding layers of hexagons and pentagons until they have completed the sphere on their own.

 

Picture of a Buckyball model taking shape in The Hive area in the Wonder Materials: Graphene and Beyond exhibition at the Museum of Science and Industry, Manchester

 

While the proud parents photograph their child holding aloft their finished product, I point to a case in the exhibition. “Do you see that model over there?” I say. “You just made that. It’s called buckminsterfullerene, or a ‘Buckyball’. And the scientists who came up with it won a Nobel Prize for it”.

 

Picture of a Buckyball model on display in the Wonder Materials: Graphene and Beyond exhibition at the Museum of Science and Industry, Manchester

 

Parents are often impressed that we’ve managed to smuggle chemistry into playing about with magnetic shapes, but the aim of the activity is more than just tricking children into learning something they might find on an exam paper at age 16.

In fact, ‘playing about with shapes’ was key to many major scientific breakthroughs of the 20th century. Technologies including nuclear magnetic resonance (NMR) and infra-red spectroscopy allowed scientists to gather data on the molecular world. However, in order to understand what structures lay behind these data points, scientists needed to think about how the shapes of these molecules could be arranged in space.

Whilst many scientists have ‘played’ with molecular models, the discovery of the structure of buckminsterfullerene is unique, as literally playing with a geometrical toy provided the scientists who discovered it with the inspiration needed to complete a model of its structure.

At the time, Harry Kroto was more interested in stardust than soot when he collaborated with Robert Smalley and Richard Curl to blast different materials with lasers. They were doing so to measure the relative molecular masses of what they had just blasted off, so that they could use these mass spectra as references to work out what molecules they were detecting in space.

They blasted graphite to form soot, because they thought this would contain small molecules called poly-ynes. Instead, they kept getting molecules that were much larger and much more stable than expected, which the spectra suggested contained 60 carbon atoms. They therefore thought that the C60 molecule must have folded over into a spherical structure. However, graphite is formed of sheets of carbons arranged in hexagons, and ‘spherical graphite’ made only of hexagons was geometrically impossible.

The researchers were stumped. Then Kroto thought back to a spherical ‘stardome’ he had made with his children using hexagons and, crucially, pentagons. The team then created an elegant model using 20 hexagons and 12 pentagons which made geometrical and chemical sense, and was later confirmed with experimental data. This became the famous buckminsterfullerene structure, given its peculiar name after the architect Buckminster Fuller, whose geodesic domes uncannily resembled the C60 structure.

The story of this discovery shows how, when scientists struggle to untangle their experimental data, using something tangible – even a child’s toy – can help them wrap their heads around structures 1,000 times smaller than the width of a hair. And, teaching children how to think about manipulating shapes using play helps them develop the same sort of reasoning required when researching the cutting edge science of small but complicated structures, from epigenetics to the mesoscopic physics of graphene.

Who knows? Maybe one of them will draw upon playing with magnetic shapes in The Hive in a few decades’ time as inspiration when puzzling through their own research project.


Sources: University of Bristol; Royal Society of Chemistry

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