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Elementary numbers

My foundation chemistry group were struggling to grasp how to draw diagrams showing atomic structure. They could not make the connection between the atomicmass numbers and the numbers of electrons, protons and neutrons.

After a disappointing test I had to find a way to show them how it worked.

A trip to the local shop saw me searching the shelves of rarely purchased dry goods. I bought dried peas and lentils of different colours. After a few hours on the computer I finally achieved a series of five concentric circles on a sheet of A4 paper.

I gave each pupil the name, symbol, mass number and relative atomic mass of just one element. From that, with simple rules written on the board, they were asked to build the atom. Peas were the positive protons and tiny red lentils the negative electrons. PVA glue was used to stick the particles in place. The pupils with the easy atoms were soon helping others still struggling to glue 20 electrons on the correct energy levels. Nuclei grew bigger and bigger. The completed atoms are displayed as a periodic table and pupils can see the relevance of the group number. I've added some information cubes made by my Year 9, showing symbol, state, metalnon-metal, uses and properties to each element so my lab now displays its own 3D periodic table.

Linda Ellard, science teacher at Cooper School, Bicester, Oxon

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