system
Given the following post, respond as if you're commenting on Reddit:
human
If elements in groups generally share similar properties (ie group 1 elements react violently) and carbon and silicon are in the same group, can silicon form compounds similar to how carbon can form organic compounds?
gpt
Yes and no.

It is possible to create molecules with several Si-Si bonds just like with carbon, but those are less stable than Carbon bonds.

In addition Silicon Hydrogen bonds are pretty reactive.

Just compare Methane, a pretty stable and unreactive molecule, with Silane, which combusts in air without any help.

That's because the electronegativity of Silicon and Carbon are different, which affects the Si-H bond.

  


As the other people mentioned Silicon Oxygen bonds are quite stable, that's what Silicone (the polymer) is.

  


  


Still, Carbon is the only known element that forms "unlimited" amounts of different molecules where the Carbon is directly bound to another Carbon.

Adding a CH2 group to elongate a molecule does not make it less stable.

This is called catenation, and allows so many different carbon compounds to exist.

Silicon, ( and Sulfur and Boron) allows for limited amount of Catenation, while Carbon allows basically unlimited chain length and branching.

  


The longest silicon chain that is somewhat possible to create contains 8 Silicon atoms in a chain. Everything longer will decompose on its own, into unspecific Silicon hydride polymers.

Si8H18 is the sum formula for that.

  


In addition Carbon can form very stable double and triple bonds, the same bonds are possible with Silicon, but they are extremely unstable. the simple molecules ~~Disilane~~ Disilene and Disilyne are possible to isolate, but anything more complex falls apart.

  


  
**Tl;Dr** They are very similar, and both allow Catenation, but the addition of another electron shell in Silicon changes the properties (electronegativity) just slightly, so that longer chains get less stable, compared to Carbon chains getting more stable and bonds with Hydrogen have more of a hydride characteristic than the covalent bond between Carbon and Hydrogen.
Thus lifeforms in anyway similar to earth's life is impossible on a silicon basis.