Silicon (Si) is the second most abundant element in the Earth’s crust after oxygen. It can be found on any beach as SiO2 in sand and in many rocks. Silicon is all around us in modern life; it is used in glass, semiconductors, concrete and ceramics. Other materials, from bathroom sealants to breast implants, also contain silicon in a polymeric form.
Silicon is just below carbon in the periodic table (Figure 1). Just as there are similarities and differences between the two elements, the same is true of carbon and silicon compounds. Both carbon and silicon can form four strong covalent bonds, giving them many opportunities to combine with other elements or compounds under the right circumstances. If it can be harvested, silicon is possibly the ultimate renewable resource. The drawback is that naturally occurring silicon is only found in silica (SiO2) or as a silicate, where the silicon is covalently bonded to oxygen. Unfortunately there is no simple generic formula for a silicate. Silicates contain silcon covalently bonded to oxygen in various proportions and are often charged. Silicate minerals contain silcon and oxygen in combination with other metals, e.g. magnesium (Mg), aluminium (Al), calcium (Ca), zinc (Zn) and iron (Fe). This Si–O bond in silica and silicates is very strong and incredibly hard to break. While silicon has always been on our planet, pure silicon (Figure 2) was not isolated until 1824 and even today we have to work hard to isolate and purify silicon.
Your organisation does not have access to this article.
Sign up today to give your students the edge they need to achieve their best grades with subject expertise
Subscribe
