First published on FB 22/03/2022
It’s been a strange couple of weeks in which not a lot of stitching has got done, partly because there’s been a lot else to sort out, and partly because it feels a little like fiddling while Rome burns. Nevertheless I have a few already done but not yet posted so today I am posting one element you have seen before, albeit at the start of this project and with little in the way of explanation, alongside one new.
In a departure from the alchemical symbols of recent posts, these two patterns both represent the structures of their elements, or to be more precise they both represent one of the several structural forms (allotropes) these elements can each take.
Carbon is represented by tesselated hexagons. There is a carbon atom at each vertex, and each side represents a bond between atoms. This form of carbon is called graphene and it was made for the first time in 2004. It is only a single atom thick but is incredibly strong – about 100 times stronger than steel. This hexagonal structure is also found in the layers of graphite and in carbon nanotubes, but not in diamond.
The pattern for phosphorus represents molecules of white phosphorus, P4 which take the shape of tetrahedrons (triangular pyramids). Viewed from above, there is a phosphorus atom at each of the four vertices, and each atom is bonded to three others. White phosphorus is unstable and changes gradually to the more stable red phosphorus which has a polymeric structure. There are also some other forms. On reaction with oxygen, white phosphorous glows softly in the dark, giving rise to its name from the Greek for ‘light bearer’.
periodically.blog 