Why don't B, C, Si, have ionic forms? [closed]








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Also, why can some elements such as $\ce{Fe}$ have different ionic forms such as $\ce{Fe^{2+}}$ and $\ce{Fe^{3+}}$? What determines each form?




Boron: borates, borides. $\ce{MgB2}$ is the highest temperature BCS superconductor by a large margin.


Carbon: carbonates, carbides, hexacoordinate carbon in complexes, organolithiums, Grignard reagents, carbenium ions ($\ce{Ph3C+}$). $\ce{Al4C3}$ hydrolyzes to methane.


Silicon: silicates, aluminosilicates, silicides. Cook up silica gel in ethylene glycol plus potassium hydroxide (*NOT* in glass) to get pentacoordinate siliconate, 


<http://patentimages.storage.googleapis.com/WO1994020507A1/imgf000014_0001.png>


You asked the second half in the Physics Stack.


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