Lead to that of primary lead; some refining processes may be skipped depending on the material recycled and its potential contamination. Of the sources of lead for recycling, lead–acid batteries are the most important; lead pipe, sheet, and cable sheathing are also significant. Contrary to popular belief, pencil leads in wooden pencils have never been made from lead. When the pencil originated as a wrapped graphite writing tool, the particular type of graphite used was named "plumbago" (literally, "act for lead" or "lead mockup"). Lead metal has several useful mechanical properties, including high density, low melting point, ductility, and relative inertness.
Lead tetrachloride Lead tetrachloride Lead tetrachloride, also known as lead(IV) chloride, has the molecular formula PbCl. It is a yellow, oily liquid which is stable below 0 °C, and decomposes at 50 °C. It has a tetrahedral configuration, with lead as the central atom. The Pb–Cl covalent bonds have been measured to be 247 pm and the bond energy is 243 kJ⋅mol. Lead tetrachloride can be made by reacting lead(II) chloride PbCl, and hydrochloric acid HCl, in the presence of chlorine gas (Cl), leading to the formation of chloroplumbic acid HPbCl. It is then converted to the ammonium salt (NH)PbCl by adding