Zinc (Zn). Diagram of the nuclear composition,electron configuration,chemical data,and valence orbitals of an atom of zinc-65 (atomic number: 30),an isotope of this element. The nucleus consists of 30 protons (red) and 35 neutrons (orange). 30 electrons (white) successively occupy available electron shells (rings). 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 |