New Zealand Science Teacher

Crystallising knowledge

26/03/2014

Your science students are invited to take part in a crystal-growing competition this year.

Left: © IUCr and Wikimedia Commons.
The crystal structure of graphite (bottom) is very different from that of diamond although both are pure carbon.

When was the last time you grew crystals? The New Zealand Institute of Chemistry (NZIC) is inviting teachers and students to participate in a competition doing just that, to celebrate the International Year of Crystallography.

Upon registration, your class will receive a sample of potassium aluminium sulfate (alum), and instructions on how to grow big crystals. There will be separate prizes for intermediate school entries, junior high school (Years 9–10), and senior high school (Years 11–13).

The Special Education group at NZIC will judge the crystals and the winning entries will be on display at the International Science Festival in Dunedin in July.

Competition coordinator Dr David McMorran says the event is a fun and hands-on way to raise awareness of the crystallography.

UNESCO’s International Year of Crystallography

2014 marks the International Year of Crystallography. The science of crystals – familiar to everyone in the form of gemstones and snowflakes – is relatively unknown to the general public, despite it underpinning all of the other science disciplines. This is one reason why the United Nations General Assembly (UNGA) has declared a dedicated period to raise awareness for this special branch of science.

The International Year of Crystallography also commemorates 100 years since the birth of X-ray crystallography, thanks to the work of father-and-son team William Henry and William Lawrence Bragg and Max von Laue who discovered the diffraction of X-rays by crystals. Max von Laue was awarded the 1914 Nobel Prize in Physics for his work.

UNESCO is leading and coordinating various educational activities during the year, and David says the NZIC Special Education Group is pleased to be hosting a New Zealand-based event for science students.

Why crystals?

“Although crystallography may not come up naturally as a discipline in secondary school science, the results obtained from the discipline are of course constantly being examined. It’s a very fundamental part of how we understand how molecules are put together,” he says.

“We’re in the process of putting together a website, with a lot of resources about crystallography, written at an appropriate level for school kids. The site will include videos, and links to other resources from around the world. So in addition to the crystal-growing competition, that will provide an opportunity to really get in to some of the science around the concept of crystals.

“We’re hoping that this crystal-growing competition will give kids a feel for what’s involved in the process, and deepen their understanding of crystallography.”

How are the crystals judged?

David says the crystals should take about six weeks to grow, given the limited amount of alum compound each class will be starting with.

“It’s a combination of things that creates a winning crystal. It’s to do with how big, heavy, and well-formed you can get them, and the aim is to create a single crystal.”

In this instance, all the atoms or molecules are lined up in exactly the same way, throughout the entire piece, as opposed to a familiar piece of quartz, made up of various crystals connected together.

Schools are to send their crystals directly to the judges in Dunedin, and David says cotton wool inside a Kinder Surprise Egg container might be the best way to package them on their journey down South. There will be information about packaging and posting on the website as well as other useful information.

Visit the Otago outreach site for more information about the crystal competition.