On the periodic table, Si is found under the element Carbon. Because it is in the same family as Carbon (Group 14 or 4A, as seen to the right), it shares many similar chemical properties as Si. All life as we know it has been carbon based, but scientists have long speculated that Si based life might be possible in other solar systems. While it might not be likely, it still fuels science fiction.

p45

"The longest nontechnical word in the Oxford English Dictionary is the forty-five-letter “pneumonoultramicroscopicsilicovolcanoconiosis,” a disease that has “silico” at its core."

"But p45 provides lessons in practical chemistry that dash hopes for silicon life. Obviously silicon life forms would need to shuttle silicon into and out of their bodies to repair tissues or whatever, just as earth-based creatures shuttle carbon around. On earth, creatures at the base of the food chain (in many ways, the most important forms of life) can do that via gaseous carbon dioxide. Silicon almost always bonds to oxygen in nature, too, usually as SiO2 . But unlike carbon dioxide, silicon dioxide (even as fine volcanic dust) is a solid, not a gas, at any temperature remotely friendly to life. (It doesn’t become a gas until 4,000°F!) On the level of cellular respiration, breathing solids just doesn’t work, because solids stick together. They don’t flow, and it’s hard to get at individual molecules, which cells need to do. Even rudimentary silicon life, the equivalent of pond scum, would have trouble breathing, and larger life forms with multiple layers of cells would be even worse off. Without ways to exchange gases with the environment, plant-like silicon life would starve and animal-like silicon life would suffocate on waste, just like our carbon-based lungs are smothered by p45." The Disappearing Spoon (Sam Kean)