We use first-principles density functional theory based calculations to determine the energetics ofgraphene and properties of silicene, a graphene-like structure made from silicon, and explorepossibilities of modifying its structure and properties to determine the likeness and dissimilaritiesbetween graphene. Our calculations are based on the generalised gradient approximation of thePerdew-Burke-Ernzerhof (GGA-PBE). Our results shown that using quantum espresso thatgraphene (carbon) is more stable compare to silicene evident from both the value of the minimumenergy and cohesive energy, and that while pure silicene is stable in a distorted honeycomb latticestructure obtained by opposite out-of-plane displacements of the two Si sub-lattices, its electronicstructure still exhibits linear dispersion with the Dirac-conical feature similar to graphene. Keywords: Silicene, graphene, minimum and cohesive energy