Lead (Pb). Diagram of the nuclear composition and electron configuration of an atom of lead-208 (atomic number: 82), the most common isotope of this element. The nucleus consists of 82 protons (red) and 126 neutrons (yellow). 82 electrons (white) bind to the nucleus, successively occupying available electron shells (rings). The stability of an element's outer electrons determines its chemical and physical properties. Lead is a post-transition metal in group 14, period 6, and the p-block of the periodic table. It has a melting point of 327 degrees Celsius. Excessive exposure can cause poisoning. Uses include batteries, weights and bullets.