The electronic properties of two dimensional hexagonal silicon (silicene) are investigated using first-principles simulations. Though silicene is predicted to be a gapless semiconductor due to the sp(2)-hybridization of the Si atoms, the weak overlapping between their 3p(z) orbitals leads to a very reactive surface, resulting in a more energetically stable semiconducting surface upon the adsorption of foreign chemical species. It is predicted that silicene inserted into a graphitelike lattice, such as ultrathin AlN stacks, preserves its sp(2)-hydridization and hence its graphenelike electronic properties. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3522774] All rights reserved.