Microscopic evidence for humic acid induced changes in lead immobilization by phosphate in a counterdiffusion system.

See more Phosphorus products. Phosphorus (atomic symbol: P, atomic number: 15) is a Block P, Group 15, Period 3 element. The number of electrons in each of Phosphorus's shells is 2, 8, 5 and its electronic configuration is [Ne] 3s² 3p³. The phosphorus atom has a radius of 110.5.pm and its Van der Waals radius is 180.pm. Phosphorus is a highly-reactive non-metallic element (sometimes considered a metalloid) with two primary allotropes, white phosphorus and red phosphorus its black flaky appearance is similar to graphitic carbon. Compound forms of phosphorus include phosphates and phosphides. Phosphorous was first recognized as an element by Hennig Brand in 1669 its name (phosphorus mirabilis, or "bearer of light") was inspired from the brilliant glow emitted by its distillation.

See more Lead products. Lead (atomic symbol: Pb, atomic number: 82) is a Block P, Group 14, Period 6 element with an atomic radius of 207.2. The number of electrons in each of Lead's shells is [2, 8, 18, 32, 18, 4] and its electron configuration is [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p². The lead atom has a radius of 175 pm and a Van der Waals radius of 202 pm. In its elemental form, lead has a metallic gray appearance. Lead occurs naturally as a mixture of four stable isotopes: ²⁰⁴Pb (1.48%), ²⁰⁶Pb (23.6%), ²⁰⁷Pb (22.6%), and ²⁰⁸Pb (52.3%). Lead is obtained mainly from galena (PbS) by a roasting process. Anglesite, cerussite, and minim are other common lead containing minerals. Lead does occur as a free element in nature, but it is rare. It is a dense, soft metal that is very resistant to corrosion and poorly conductive compared to other metals. Its density and low melting point make it useful in applications such as electrolysis and industrial materials.