Question

Question #f3b71

Answer 1

Mostly because of history.

Explanation:

`CO` isn't an organic compound because the carbon isn't tetravalent, i.e.: it's oxidation state isn't `+4` which is a requirement for all organic compounds.

`CO_2` isn't an organic compound because historically speaking it was discovered before organic chemistry as a field was funded. Chemically speaking it meets most of the requirements and has some properties that make it a "little bit of column A and little bit of column B".

Carbonates in general I believe are considered inorganic - instead of organometalloids - because the crystals in general make specific ores like limestone, aragonite, chalk, marble, etc.

To be fair, most defitions are a bit drawn in the sand.
They used to say that it needs to be made (and only made) by lifeforms, but `CO_2` is made by them whereas urea, an organic compound, isn't.

The C-H rule, exclude urea and oxalic acid, which are important to biological function and were key compounds in the vitalism (previous paragraph) debate.

The C-C compound exclude methane, formaldehyde and other single-carbon compounds.