Does the field of organic chemistry cover all the other group 14 elements or does it strictly deal with Carbon chemistry? Since the other group 14 elements have similar chemical properties, such as silicon, wouldn't they fall under the same discipline? Why or why not?

  • 1
    $\begingroup$ They aren't similar at all. $\endgroup$
    – Mithoron
    Oct 6 '18 at 16:13
  • $\begingroup$ This is pretty much reposting! chemistry.stackexchange.com/questions/82318/… $\endgroup$
    – Mithoron
    Oct 6 '18 at 16:17
  • $\begingroup$ Yes, but my question was closed because it my question was "unclear." You're welcome to vote to have it removed. $\endgroup$
    – user148298
    Oct 11 '18 at 4:34

The other group 14 elements don't have similar chemistry. In general, the elements in the 2p block are "unusual" compared to the 3p/4p/5p blocks, just as how the elements in the 3d block are quite different compared to the 4d/5d blocks, and just as how hydrogen ("1s block") is very different from the alkali metals.

The obvious difference in chemistry comes from the unparalleled ability of carbon to catenate, or in other words, to form chains of single bonds. Silicon does not do this to any appreciable extent, mainly due to bond energetics (the Si–Si bond, for example, is much weaker than C–C).

Many of the functional groups familiar to organic chemistry have little parallel in silicon chemistry. Carbonyl groups are ubiquitous, but Si=O compounds are barely stable (see Wikipedia), which is a result of the poor π overlap between Si (valence 3p orbitals) and O (valence 2p). The same applies for C=C and C≡C bonds. Silicon analogues are known, but are very difficult to make and generally need to be stabilised using a variety of tricks (see: How come there aren't any silicon analogs of alkenes or alkynes? and links within).

So, traditionally, the chemistry of Si/Ge/Sn/Pb is within the realm of inorganic chemistry. Of course, it is never a clear-cut distinction, since these elements can coexist with carbon in the same molecule. But that is a story for another time.

  • $\begingroup$ Or rather, they don't have similar chemistry under room conditions. Since we mostly care about stuff that exists in the same temperatures and pressures as us, carbon utterly dominates. $\endgroup$
    – Luaan
    Oct 6 '18 at 12:20
  • $\begingroup$ @Luaan, a fair amount of organic chemistry deals with high or low temperatures or pressures. Although biological systems are indeed important, organic chemistry isn't solely about them or how close we can get to them. Furthermore, I don't think that C/Si chemistry is any more similar at 4 K than it is at 298 K, although I am open to being corrected on this. $\endgroup$
    – orthocresol
    Oct 6 '18 at 12:27
  • $\begingroup$ It deals with those temperatures and pressures mainly to increase the production yield of compounds stable at normal temperatures and pressures, doesn't it? And I've read a few papers suggesting conditions under which silicon behaves similar to carbon (while carbon no longer does, of course), but I can't find the references right now. I'll see if I can find something. $\endgroup$
    – Luaan
    Oct 6 '18 at 15:10
  • $\begingroup$ Yeah, fair enough, that makes sense! $\endgroup$
    – orthocresol
    Oct 6 '18 at 15:11
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    $\begingroup$ @user148298, yes, these are known. Si–O and Si–N single bonds are pretty strong and don't simply fall apart, so stuff such as HMDS are pretty stable. Silyl ethers are very stable too. $\endgroup$
    – orthocresol
    Oct 6 '18 at 15:24

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