Thread: Any other candidates?

Do any other posters know of an element other than carbon suitable to construct the large, complex molecules necessary fo life processes? I have looked at Mendelov's periodic chart of the elements and have found no other element. Carbon has a half empty outer shell, with the maximum number of valences to make linkages with other elements.

Greg858

Any element in the same group(14, or IVA, however you'd like to look at it), such as Si, bonds in the same way, so they would kind of work, but their characteristics aren't quite the same, so I doubt they'd work, given how specific things have to be for biological molecules to function...

Silicon has the potential, at least in theory, to form complex compounds analogous to carbon compounds. The problem is that such silicon bonds are much less stable than in their carbon models. In fact, such compounds would decompose in water. Therefore a silicon-based life system could not endure in an aqueous environment.

Originally Posted by Chemboy

Any element in the same group(14, or IVA, however you'd like to look at it), such as Si, bonds in the same way, so they would kind of work, but their characteristics aren't quite the same, so I doubt they'd work, given how specific things have to be for biological molecules to function...

You had given me some hope, only to dash it as you elaborated. My education and intellect are wanting, so I am trying to enlist better, more trained minds to aid me. Thanks for the help. :wink:

[quote="SteveF"]Silicon has the potential, at least in theory, to form complex compounds analogous to carbon compounds. The problem is that such silicon bonds are much less stable than in their carbon models. In fact, such compounds would decompose in water. Therefore a silicon-based life system could not endure in an aqueous environment.[/quote

Steve, you said that silicon linkages would come apart in an aquious envionment. I don't know what is meant by aquious? Would they also fall apart in another medium that was liquid at the temperatures that would allow biologic chemical reactions proceed at the right rate? The only substances that I know of that would be a liquid at any reasonable atmospheric pressure at suitable temporatures are alcahols and some hydrocarbons.

If I sound like I don't know what I'm talking about, this is because I don't. Please explain your musings on this possibility?

Greg858

Aqueous simply means water, or any solution that consists mostly of water. Chemists are always talking about "aqueous solutions" to distinguish them from organic solutions. The latter do not contain water.

For the record, all terrestrial life is water-based. If you want to imagine silicon-based lifeforms they would have to occur in an environment with no liquid water. So far, I don't know if any chemist has proposed such a system.

Originally Posted by SteveF

Aqueous simply means water, or any solution that consists mostly of water. Chemists are always talking about "aqueous solutions" to distinguish them from organic solutions. The latter do not contain water.

For the record, all terrestrial life is water-based. If you want to imagine silicon-based lifeforms they would have to occur in an environment with no liquid water. So far, I don't know if any chemist has proposed such a system.

Thanks, Steve. I needed expert conformation on what I suspected.

Greg858