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

The Question

Becky asks:

Follow-up question.

Given:
-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.

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

(figures taken from http://education.jlab.org/glossary/abund_ele.html)

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
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    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.

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  • 3/21/2006 at 12:59 pm
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    I remember that episode – the main scientist from the volcano was played by “Josh” from The West Wing.

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  • 3/21/2006 at 1:04 pm
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    Wow! SMcQuaid will answer your questions even if you didn’t ask on directly!

    Excellent WestWing/XFiles factoid Shaun!

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  • 3/21/2006 at 8:50 pm
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    He’s just trying to compensate for not remembering the X Files episode before I posted about it ;)

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  • 3/24/2006 at 8:19 am
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    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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