At GCSE level many pupils struggle with the concept of chemical structure. Interestingly, at atomic level they can draw atoms, ions and molecules (and the bonds between them ) but ask them to arrange these particles into three dimensional structures and explain the properties that arise and their understanding falls apart. If only we had special googles that allowed them to see arrangements of atoms and ions in a three dimensional structure and a chemistry teacher’s life would be so much easier.
So why is structure so important and how can we illustrate this to our pupils ? A recent display on the elements at the Ulster Museum linked the different elements silicon, copper and iron to human progress. We have had the Stone Age (silicon), Bronze Age (copper), Iron Age, and then reversing them for the industrial revolution (iron), electrical and telecommunications (copper) and of course the current silicon age. Quizzing pupils about these elements showed that there was little understanding of the link between elemental silicon and their lifestyles. Silicon is found in the same group as carbon with four valence electrons. It forms a giant covalent structure, very similar to diamond, with the valence electrons used in covalent bonding. So how does this structure contribute to our technologically advanced lifestyle – very simply by changing (doping) some silicon atoms to electron rich (phosphorus) or electron poor ( boron) atoms we can create a semi-conductor.
The natural progression from silicon to doped silicon to transistors to chips is what has made microprocessors and other electronic devices so inexpensive and prevalent in today’s society.
Now it looks like the man who made his fortune thanks to silicon recognises the importance of a material’s structure too – Bill Gates tweeted a link to a book he has read and loved recently.
Mark Miodownik’s book ‘Stuff Matters’ discusses the structures of both basic materials such as paper and glass and also the new super materials that will change the way we live. As Bill says once you understand structures ‘You’ll Never Look at a Pencil, Teacup, or Razor Blade the Same Way’