  Silicene and Graphene are similar and have $\pi$-$\pi^*$ bands. However band
width in silicene is only a third of graphene. It results in a substantial
increase in the ratio of Hubbard U to band width W, U/W $\sim$ 0.5 in graphene
to $\sim 1$ in silicene. This enhancement, 2 dimensionality and phenomenology
suggest a Mott insulator based ground state for silicene (G. Baskaran,
arXiv:1309.2242). We lend support to the above proposal by showing, in an
ab-initio calculation, that unlike graphene, silicene has two instabilities: i)
a valence bond (Kekule) dimerization and ii) a weak two sublattice
antiferromagnetic order. Presence of these instabilities, in the absence of
fermi surface nesting, point to Mott localization, \textit{within the frame
work of ab-initio scheme}. Substrate dependent structural reconstructions seen
experimentally in silicene are interpreted as generalized Kekule bond order.
