Silicone oil

Silicone oils (polymerized siloxanes) are silicon analogues of carbon based organic compounds, and can form (relatively) long and complex molecules based on silicon rather than carbon. Chains are formed of alternating silicon-oxygen atoms (...Si-O-Si-O-Si...) or siloxane, rather than carbon atoms (...C-C-C-C...). Other species attach to the tetravalent silicon atoms, not to the divalent oxygen atoms which are fully committed to forming the siloxane chain.

A typical example is polydimethylsiloxane, where two methyl groups attach to each silicon atom to form (H3C)[SiO(CH3)2]nSi(CH3). The carbon analogue would be an alkane, e.g. dimethylpropane C5H12 or (H3C)[C(CH3)2](CH3)

Silicone could be a basis for silicon-based organic life, as opposed to silicon based artificial life in computers. But their more prosaic, primary uses are as lubricants or hydraulic fluids. They are excellent insulators and, unlike their carbon analogues, are non flammable.