Electrochemical reduction of carbon-dioxide/carbon-monoxide (CO(2)R) to fuels and chemicals presents an attractive approach for sustainable chemical synthesis, but also poses a serious challenge in catalysis. Understanding the key aspects that guide CO(2)R towards value-added multicarbon (C2+) products is imperative in designing an efficient catalyst. Herein, we identify the critical steps toward C2 products on copper through a combination of energetics from density functional theory and micro-kinetic modeling. We elucidate the importance of atomic carbon in directing C2+ selectivity and how it introduces surface structural sensitivity on copper catalysts. This insight enables us to propose two simple thermodynamic descriptors that effectively describe C2+ selectivity on metal catalysts beyond copper and hence it identifies an intelligible protocol to screen for materials that selectively catalyze CO(2) to C2+ products.