diagonal relationship?

Question

Can anyone explain the diagonal-relationship between B and Si???
thx million

Answer 1

This is best understood in terms of them both being on the borderline between metals and non-metals - in particular, the fact that their oxides are acidic.
Boron is quite different to silicon in respect of the fact that its simple covalent compounds are electron-deficient, that is they only have six electrons in the outer level. Thus they are strong Lewis acids.
Silicon can accept electron pairs, but only by expanding its valency octet.