Seznamy Atom Zinc Zdarma . Zinc oxide (zno), a common zinc compound, forms when metallic zinc is exposed to the air and forms a protective coating that protects the rest of the metal. In the higher energy (49.0 kj mol −1) singlet state b, the zinc atom donates an electron pair from its 4 s orbital into the empty sp3 orbital on ch 2. Sources, facts, uses, scarcity (sri), podcasts, alchemical symbols, videos and images. Both elements exhibit only one normal oxidation state (+2), and the zn2+ and mg2+ ions are of similar size.