The key difference between silicon and silica is that silicon is a chemical element whereas silica is a chemical compound.
Silica is a common oxide form of silicon. Silicon is commercially prepared using silica in an electric arc furnace. Both silica and silicon have lattice structures. But silica differs from silicon due to the presence of silicon-oxygen covalent bonding. This accounts for all the different properties between the two.
What is Silicon?
Silicon is the element with atomic number 14, and it is also in group 14 of the periodic table, just below carbon. Its symbol is Si and electron configuration is 1s2 2s2 2p6 3s2 3p2. Silicon can remove four electrons and form a +4 charged cation, or it can share these electrons to form four covalent bonds.
We can characterize silicon as a metalloid because it has both metal and nonmetal properties. Furthermore, it is a hard and inert metalloid solid. The melting point of silicon is 1414 oC, while the boiling point is 3265 oC. Crystal-like silicon is very brittle. It exists very rarely as pure silicon in nature. Mainly, it occurs as the oxide or silicate.
Since silicon is protected with an outer oxide layer, it is less susceptible to chemical reactions. High temperatures are needed for it to oxidize. However, silicon reacts with fluorine at room temperature. Silicon does not react with acids but reacts with concentrated alkalis. There are a lot of industrial uses of silicon. Silicon is a semiconductor: therefore, it is mainly important in computers and electronic devices.
What is Silica?
Silicon exists as its oxide in nature, and we name as silica. Silica has the molecular formula of SiO2 (silicon dioxide). It is an abundant mineral on the earth crust, and it is the major component in sand, quartz, and many other minerals. Some minerals have pure silica, but some silica is mixed with other elements.
In silica, silicon and oxygen atoms join each other by covalent bonds to form a huge crystal structure. Each silicon atom has four oxygen atoms surrounding it (tetrahedrally). Silica doesn’t conduct electricity because there aren’t any delocalized electrons. Furthermore, it is highly thermo-stabilized. Silica has a very high melting point because a large number of silicon-oxygen bonds have to be broken in order to melt it. When we give a very high temperature and cool at a certain rate, the molten silica will solidify to form glass. Silica doesn’t react with any acid except hydrogen fluoride. Moreover, it is not soluble in water or any organic solvent.
Not only silica is abundant in the earth crust, but it is also present inside our bodies in considerable amounts. We need this compound for the healthy maintenance of bones, cartilages, nails, tendons, teeth, skin, blood vessels, etc. It is naturally present in water, carrot, bread, cornflakes, white rice, banana, raisin, etc. Moreover, silica is very important in ceramic, glass and cement industries.
What is the Difference Between Silicon and Silica?
Silicon and silica are two different chemical species. The key difference between silicon and silica is that silicon is a chemical element whereas silica is a chemical compound. Silica has a higher melting point than silicon. Further, Silicon is a semiconductor, but silica doesn’t conduct electricity. Another difference between silicon and silica is that silicon very rarely exists as a pure compound while silica is abundant on earth. Moreover, crystal silicon is very brittle, but crystal silica is hard.
Summary – Silicon vs Silica
The key difference between silicon and silica is that silicon is a chemical element whereas silica is a chemical compound. Both silica and silicon have lattice structures. But silica differs from silicon due to the presence of silicon-oxygen covalent bonding. This accounts for the basic difference between silica and silicon.
1. “Silica.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 2 Aug. 2019, Available here.