Why don't we have Si based living systems on Earth?

Question

instead of carbon based organisms

Answer 1

Si looks like C, but it does not mean Si-life can exist.

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Answer 2

Silicon-based life could occur either silicon (i.e. neutral molecules containing Si-Si covalent bonds) or silicate (polar molecules with Si-O-Si bonds) based.

Silicon and hydrogen can form silanes which are somewhat stable in the absence of water. However, oligo-silanes (i.e. silanes with functional groups like -OH, -NH2, etc as known from organic chemistry) tend to be unstable because the disproportioned product (e.g. SiO2 and Silane)

Silicate chemistry tends to be slow, geologically slow is a stringent phrase. However, under hydrothermal conditions (watery solution at high pressure, around 500-600K), silicates get a lot more reactive, and silicate molecules (or ions) can remain in solution for meaningful times.

Again, functional groups make life difficult. Heteroatoms Al and P can be introduced into the chains and create charged centers which may allow to carry functional ligands, or directly act as such.

In such a basic chemical soup, life would require a means of generating and processing chemical energy, and a means to store the programming. It is quite miraculous that such means were found with carbon chemistry, for silicate chemistry on Earth it would be more miraculous. Thermosynthesis using geothermal energy could be a basis for such a life cycle, if one could build an equivalent of sugars and proteins from silicate-based molecules which don't crystallize at their earliest convenience.

Answer 3

2 reasons.. 1. the heat and light requirements of reactions of silicon are too great to occur in cool low light earth atmosphere. 2. God made earth specifically for this carbon based system of living entities..

Answer 4

Do "ThEy" have Si based living systems on other planets?