Provided are functionalized silicon compounds and methods for their synthesis and use. The functionalized silicon compounds include at least one activated silicon group and at least one derivatizable functional group. Exemplary derivatizable functional groups include hydroxyl, amino, carboxyl and thiol, as well as modified forms thereof, such as activated or protected forms. The functionalized silicon compounds may be covalently attached to surfaces to form functionalized surfaces which may be used in a wide range of different applications. In one embodiment, the silicon compounds are attached to the surface of a substrate comprising silica, such as a glass substrate, to provide a functionalized surface on the substrate, to which molecules, including polypeptides and nucleic acids, may be attached. In one embodiment, after covalent attachment of a functionalized silicon compound to the surface of a solid silica substrate to form a functionalized coating on the substrate, an array of nucleic acids may be covalently attached to the substrate. Thus, the method permits the formation of high density arrays of nucleic acids immobilized on a substrate, which may be used, for example, in conducting high volume nucleic acid hybridization assays.