Tag: Diamond

Last time we started talking about the allotropes of carbon, finished graphite and began with diamond.  Tonight we shall continue the diamond saga and maybe move to a third common allotrope.

Last week I was having some connectivity problems and, quite frankly, was ill with a bad cold, so I just did not feel much like writing.  I am better (much) this week and my computer seems to be functioning within design parameters.

Since the part that I wrote about diamond was so short last time, I shall paraphrase it as the start of this piece.  That way you do not have to hit the link to get up to speed.

Last time we started our series on carbon, and I now expect it to run for four installments.  Amongst many other properties, carbon is unique in having more allotropic forms than any other element.  Also known as allotropes, these are pure elements with radically different properties.  The term is reserved only for elements, the term for compounds being polymorphs.  An allotrope is a subset of a polymorph.

There is also another distinction:  for an element to have an allotrope, it must exist in the same phase.  Thus, solid lead and molten lead (and lead vapor) are not allotropes, but rather different phases of a given element.

Before we concentrate on carbon, let us consider oxygen.  In the gaseous phase, it has two allotropes, O₂, normal molecular oxygen, and O₃, also called ozone.  For an element as reactive as oxygen, normal molecular oxygen is remarkably nonreactive (wait a few weeks), but ozone is extremely reactive.  But both are just composed of oxygen atoms.