In the Periodic Table, directly beneath carbon lies an element we seldom think about, even though it is all around us. That element is silicon. Its compounds account for more than 90% of the Earth's crust and it is estimated to be the eighth most common element in the universe by mass. Going down the column of materials beneath carbon, after silicon comes the metalloid germanium, followed by tin and lead, which are clearly metals. However, carbon is clearly not a metal, so where does silicon belong? It has a "neither fish nor flesh" attribute and that makes it very interesting.
As we sit on the beach, or look out our windows, we are confronted with silica, the dioxide of silicon, a solid material utterly unlike the much-maligned gaseous dioxide of carbon, the element immediately above it in the Periodic Table. We tend to think of silicon as more like metals than like carbon, especially when we see it used in photocell applications. Controversy about silicon's character dates back to its discovery. In 1808, it was given the name silicium, with the -ium word-ending suggesting to be a metal. However, its final English name, first suggested in 1817, reflects the more physically similar elements carbon and boron. It was first prepared and characterized in pure form in 1823.
Though less reactive than its chemical analog carbon, silicon shares with it the ability to form chemical bonds with four hydrogen atoms arranged at the corners of a tetrahedron. The simple compound SiH4 is analogous to methane, CH4 and so is called monosilane. Although...