Diagram of the nuclear composition, electron configuration, and valence orbitals of an atom of zinc-65 (atomic number: 30), an isotope of this element. The nucleus consists of 30 protons (blue) and 35 neutrons (red). Zinc is a transition metal in group 12, period 4, and the d-block of the periodic table. It has a melting point of 419 degrees Celsius, a much lower melting point than most of the other transition metals, since the d-subshell shielding effect on outer (valence) electrons ends. Zinc, present in many biological enzymes, is an essential mineral in the diet. |