In the United States, the permissible exposure limit for lead in the workplace, comprising metallic lead, inorganic lead compounds, and lead soaps, was set at 50μg/m 3 over an 8-hour workday, and the blood lead level limit at 5μg per 100g of blood in 2012. [308] Lead may still be found in harmful quantities in stoneware, [309] vinyl [310] (such as that used for tubing and the insulation of electrical cords), and Chinese brass. [u] Old houses may still contain lead paint. [310] White lead paint has been withdrawn from sale in industrialized countries, but specialized uses of other pigments such as yellow lead chromate remain. [182] Stripping old paint by sanding produces dust which can be inhaled. [312] Lead abatement programs have been mandated by some authorities in properties where young children live. [313] The extraction, production, use, and disposal of lead and its products have caused significant contamination of the Earth's soils and waters. Atmospheric emissions of lead were at their peak during the Industrial Revolution, and the leaded gasoline period in the second half of the twentieth century. [291] Lead can accumulate in soils, especially those with a high organic content, where it remains for hundreds to thousands of years. Environmental lead can compete with other metals found in and on plant surfaces potentially inhibiting photosynthesis and at high enough concentrations, negatively affecting plant growth and survival. Contamination of soils and plants can allow lead to ascend the food chain affecting microorganisms and animals. In animals, lead exhibits toxicity in many organs, damaging the nervous, renal, reproductive, hematopoietic, and cardiovascular systems after ingestion, inhalation, or skin absorption. [295] Fish uptake lead from both water and sediment; [296] bioaccumulation in the food chain poses a hazard to fish, birds, and sea mammals. [297] However, lead flashing has an incredible lifespan in excess of 100 years, meaning that if it is kept in good shape with a routine clean once or twice a year, you won’t have to go through the expensive process of removing, repairing, or replacing your lead for up to century.

Apart from the stable isotopes, which make up almost all lead that exists naturally, there are trace quantities of a few radioactive isotopes. One of them is lead-210; although it has a half-life of only 22.2 years, [35] small quantities occur in nature because lead-210 is produced by a long decay series that starts with uranium-238 (that has been present for billions of years on Earth). Lead-211, −212, and −214 are present in the decay chains of uranium-235, thorium-232, and uranium-238, respectively, so traces of all three of these lead isotopes are found naturally. Minute traces of lead-209 arise from the very rare cluster decay of radium-223, one of the daughter products of natural uranium-235, and the decay chain of neptunium-237, traces of which are produced by neutron capture in uranium ores. Lead-210 is particularly useful for helping to identify the ages of samples by measuring its ratio to lead-206 (both isotopes are present in a single decay chain). [49] Former US President Donald Trump reimposed sanctions on Iran’s oil industry in 2018, but Iranian oil exports and output rose in 2022 and 2023 as Washington and Tehran resumed talks over the Islamic republic’s controversial nuclear programme. Smelting, which is an essential part of the primary production, is often skipped during secondary production. It is only performed when metallic lead has undergone significant oxidation. [195] The process is similar to that of primary production in either a blast furnace or a rotary furnace, with the essential difference being the greater variability of yields: blast furnaces produce hard lead (10% antimony) while reverberatory and rotary kiln furnaces produce semisoft lead (3–4% antimony). [207] The first is an effect called leaching. This is when a substrate filled with moisture like concrete or wood starts slowly taking tiny amounts of lead and depositing it in the concrete. This is a huge issue because it causes the lead sheeting itself to slowly become fragile as it hollows out.

About Lead

Because silver was extensively used as a decorative material and an exchange medium, lead deposits came to be worked in Asia Minor from 3000BC; later, lead deposits were developed in the Aegean and Laurion. [130] These three regions collectively dominated production of mined lead until c. 1200BC. [131] Beginning c. 2000BC, the Phoenicians worked deposits in the Iberian peninsula; by 1600BC, lead mining existed in Cyprus, Greece, and Sardinia. [132] Ancient Greek lead sling bullets with a winged thunderbolt molded on one side and the inscription ΔΕΞΑΙ ("take that" or "catch") on the other side [133] A lead atom has 82 electrons, arranged in an electron configuration of [ Xe]4f 145d 106s 26p 2. The sum of lead's first and second ionization energies—the total energy required to remove the two 6p electrons—is close to that of tin, lead's upper neighbor in the carbon group. This is unusual; ionization energies generally fall going down a group, as an element's outer electrons become more distant from the nucleus, and more shielded by smaller orbitals. Lead mining in Western Europe declined after the fall of the Western Roman Empire, with Arabian Iberia being the only region having a significant output. [161] [162] The largest production of lead occurred in South and East Asia, especially China and India, where lead mining grew rapidly. [162] From 1960 to 1990, lead output in the Western Bloc grew by about 31%. [188] The share of the world's lead production by the Eastern Bloc increased from 10% to 30%, from 1950 to 1990, with the Soviet Union being the world's largest producer during the mid-1970s and the 1980s, and China starting major lead production in the late 20th century. [189] Unlike the European communist countries, China was largely unindustrialized by the mid-20th century; in 2004, China surpassed Australia as the largest producer of lead. [190] As was the case during European industrialization, lead has had a negative effect on health in China. [191] Production [ edit ] Primary production of lead since 1840

The sum of the first four ionization energies of lead exceeds that of tin, [7] contrary to what periodic trends would predict. This is explained by relativistic effects, which become significant in heavier atoms, [8] which contract s and p orbitals such that lead's 6s electrons have larger binding energies than its 5s electrons. [9] A consequence is the so-called inert pair effect: the 6s electrons of lead become reluctant to participate in bonding, stabilising the +2 oxidation state and making the distance between nearest atoms in crystalline lead unusually long. [10]

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Lead is a relatively unreactive post-transition metal. Its weak metallic character is illustrated by its amphoteric nature; lead and lead oxides react with acids and bases, and it tends to form covalent bonds. Compounds of lead are usually found in the +2 oxidation state rather than the +4 state common with lighter members of the carbon group. Exceptions are mostly limited to organolead compounds. Like the lighter members of the group, lead tends to bond with itself; it can form chains and polyhedral structures.

Traditionally, bossing tools for Leadwork, were made from hardwoods such as Beech, Hornbeam, and Boxwood. Lead's lighter carbon group congeners form stable or metastable allotropes with the tetrahedrally coordinated and covalently bonded diamond cubic structure. The energy levels of their outer s- and p-orbitals are close enough to allow mixing into four hybrid sp 3 orbitals. In lead, the inert pair effect increases the separation between its s- and p-orbitals, and the gap cannot be overcome by the energy that would be released by extra bonds following hybridization. [11] Rather than having a diamond cubic structure, lead forms metallic bonds in which only the p-electrons are delocalized and shared between the Pb 2+ ions. Lead consequently has a face-centered cubic structure [12] like the similarly sized [13] divalent metals calcium and strontium. [14] [a] [b] [c] Bulk [ edit ] Gauges to regulate the supply of each gas to the torch. usually, 1 bar oxygen to 0.5 bar Acetylene. Bulk lead exposed to moist air forms a protective layer of varying composition. Lead(II) carbonate is a common constituent; [51] [52] [53] the sulfate or chloride may also be present in urban or maritime settings. [54] This layer makes bulk lead effectively chemically inert in the air. [54] Finely powdered lead, as with many metals, is pyrophoric, [55] and burns with a bluish-white flame. [56] Lead waste, depending on the jurisdiction and the nature of the waste, may be treated as household waste (to facilitate lead abatement activities), [314] or potentially hazardous waste requiring specialized treatment or storage. [315] Lead is released into the environment in shooting places and a number of lead management practices have been developed to counter the lead contamination. [316] Lead migration can be enhanced in acidic soils; to counter that, it is advised soils be treated with lime to neutralize the soils and prevent leaching of lead. [317]In Bangladesh, lead compounds have been added to turmeric to make it more yellow. [283] This is believed to have started in the 1980s and continues as of 2019 [update]. [283] It is believed to be one of the main sources of high lead levels in the country. [284] In Hong Kong the maximum allowed lead parts per million is 6 in solid foods and 1 in liquid foods. [285] For example, if you were fixing a concrete coping stove to then cover in lead, the fixings used to secure the coping should be stainless steel. Thermal insulation materials for leadwork Unlike the spike in oil prices that followed Russia’s invasion of Ukraine last year, the fighting between Israeli soldiers and Hamas fighters, which has killed more than 1,500 people so far in Israel and Gaza, does not directly involve oil-producing nations. Oil underneath flashings to 50mm from the edge and under any clips to prevent the carbonate forming at the join Lead(II) compounds are characteristic of the inorganic chemistry of lead. Even strong oxidizing agents like fluorine and chlorine react with lead to give only PbF 2 and PbCl 2. [54] Lead(II) ions are usually colorless in solution, [62] and partially hydrolyze to form Pb(OH) + and finally [Pb 4(OH) 4] 4+ (in which the hydroxyl ions act as bridging ligands), [63] [64] but are not reducing agents as tin(II) ions are. Techniques for identifying the presence of the Pb 2+ ion in water generally rely on the precipitation of lead(II) chloride using dilute hydrochloric acid. As the chloride salt is sparingly soluble in water, in very dilute solutions the precipitation of lead(II) sulfide is instead achieved by bubbling hydrogen sulfide through the solution. [65]

What patination oil does is essentially act as an artificial patina over the flashing. All oils are hydrophobic, or water repelling. This patina protects the flashing from water. Patination oil should be applied just after lead is applied. In fact, patination oil should be considered the final part of the application process. Doing it immediately gives no time for lead carbonate to build up.The Middle East is home to some of the world’s biggest major oil producers, including Iran and Saudi Arabia, as well as key transit routes such as the Strait of Hormuz, which is known as the world’s most important “oil chokepoint”. Will oil prices keep rising for the foreseeable future? When undertaking lead work, especially when forming details, it is not always possible to use a wood roll to form a mechanical joint. While neither Israel nor the besieged Gaza Strip are significant oil producers, markets have been jolted by fears that the conflict could lead to wider regional instability.