Q.14
Which one of the following compounds is known as silanes?
Options:
(A) Silicon hydrides
(B) Silicon halides
(C) Silicon hydroxides
(D) Silicon oxides
Silanes represent a fundamental class of silicon compounds analogous to alkanes in carbon chemistry, critical for semiconductor manufacturing, chemical vapor deposition (CVD), and organosilicon synthesis. The question tests precise nomenclature in inorganic and materials chemistry.
The correct answer is (A) Silicon hydrides, as silanes are specifically defined as compounds containing Si-H bonds, primarily binary silicon-hydrogen compounds like SiH₄ (silane), Si₂H₆ (disilane).
Why (A) Silicon Hydrides Defines Silanes
Silanes follow the general formula SiₙH₂ₙ₊₂, mirroring hydrocarbons. Monosilane (SiH₄) serves as the parent compound, used in silicon wafer production and ALD processes. The term strictly refers to silicon-hydrogen compounds, distinguishing them from other silicon derivatives.
Explanation of All Options
Each option represents distinct silicon compound classes:
-
(A) Silicon hydrides
Correct. Silanes = SiH₄, Si₂H₆, etc. Contain characteristic Si-H bonds; structural analogs of alkanes but less stable and pyrophoric. -
(B) Silicon halides
Incorrect. These are SiX₄ compounds (X = F, Cl, Br, I) like SiCl₄ (tetrachlorosilane), used as CVD precursors but lack Si-H bonds. Called halosilanes. -
(C) Silicon hydroxides
Wrong. Silicates or silanols (R₃SiOH) contain Si-OH groups. No relation to silane nomenclature. -
(D) Silicon oxides
No. SiO₂ (silica/quartz) and siloxanes (R₂SiO) contain Si-O bonds. Fundamental materials but not silanes.
Quick Classification Table
| Option | Compound Class | General Formula | Examples | Is Silane? |
|---|---|---|---|---|
| A | Silicon hydrides | SiₙH₂ₙ₊₂ | SiH₄, Si₂H₆ | Yes |
| B | Silicon halides | SiX₄ | SiCl₄, SiF₄ | No |
| C | Silicon hydroxides | R₃SiOH | Trimethylsilanol | No |
| D | Silicon oxides | SiO₂, R₂SiO | Quartz, PDMS | No |
Biotech relevance: Silanes form self-assembled monolayers (SAMs) for biosensors and immobilize biomolecules on silicon surfaces. Master by remembering: Si-H bonds = silanes; everything else gets different nomenclature.
