DEFY S. McQUAID! #59: Silicon VS. Carbon

The Question

Becky asks:

Follow-up question.

-Life on Earth is Carbon based.
-The second most common element in the earth’s crust is Silicon (28% by weight, Oxygen is first).
-Silicon Dioxide is the most common compound (42% by weight).
-Carbon and Silicon both have room for 4 electrons on their outer orbitals, so their affinity for electrons should be equal.

Why is life on Earth Carbon based instead of Silicon based?

(figures taken from

The Answer

Another question from the elegant, intelligent Becky. I relish the challenge.

The answer lies in the fact that carbon knows how to party and get along with others of its kind. Silicon is a poor partier and an angry drunk, so it gets left out of the life-shindig. Carbon is very comfortable hanging out in multiple configurations with other carbon molecules (chains, links, etc) – silicon, when put in the same configuration, tends to either fall apart or EXPLODE. While an exploding life form might be interesting, it’s likely to be short-lived.

Carbon likes to hang out in molecules of tens of thousands of atoms. Silicon, being kind of lame and boring, only hangs out at most with 6 other atoms of the same kind, and that’s only in the lab – being such big dorks and all, parties are beyond silicon’s ken.

Finally, carbon has chirility, or handedness. Most organic molecules form in left or right “handed” configurations – and silicon is a big ambidextrous loser. The chirility is what allows carbon molecules to form chains, which are required in organic compounds.

I hope this answers your question, Becky. Carbon likes to get out and party, and silicon stays at home and smells like rotten eggs.

5 thoughts on “DEFY S. McQUAID! #59: Silicon VS. Carbon

  • 3/21/2006 at 12:52 pm

    There was an X Files episode where a robot sent into a volcano came back with the spores of a silicon based life-form. It was some kind of fungi that grew in human lungs and then exploded messily out of their throat, spraying spores everywhere and infecting more victims. How a life-form that grew in human lungs evolved inside a volcano was not clear, but it was a good episode as I recall.

  • 3/21/2006 at 12:59 pm

    I remember that episode – the main scientist from the volcano was played by “Josh” from The West Wing.

  • 3/21/2006 at 1:04 pm

    Wow! SMcQuaid will answer your questions even if you didn’t ask on directly!

    Excellent WestWing/XFiles factoid Shaun!

  • 3/21/2006 at 8:50 pm

    He’s just trying to compensate for not remembering the X Files episode before I posted about it ;)

  • 3/24/2006 at 8:19 am

    For those of us who don’t watch high-brow shows like the X-files or the west wing, the actor who played that scientist was also the mean businessman in the movie “Billy Madison”.


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