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Passsivity promoters and dissolution moderators are identified among metallic elements and classified by considering two fundamental properties, which are the metal-oxygen bond strength and the metal-metal bond strength. Passivity promoters are elements which combine a high metal-oxygen bond strength (high heat of adsorption of oxygen or OH (ΔH_ads(ox)) with a low metal-metal bond energy (ε_M-M), because the transition from adsorbed O or OH overlayer to 3D oxide requires the breaking of metal-metal bonds. In contrast, dissolution moderators are expected to be elements with a high metal-metal bond energy. Groups of metals appear clearly in a diagram of ΔH_ads (oxygen) and ε_M-M.