The first ionization energy is 7.4 16 eV. The second ionization energy is 15.874 eV. The melting point is 327.5℃ and the boiling point is 1740℃. Density 1 1.3347 g/cm3. Blue and white heavy metal, soft, weak ductility and strong ductility. In the air, the surface is easy to oxidize, lose luster and become gloomy. Soluble in nitric acid, hot sulfuric acid, organic acid and lye. Insoluble in dilute acid and sulfuric acid. Amphoteric: It can form both metal salts of high lead acid and lead salts of acid. The sources of elements mainly exist in galena (PbS) and galena (PbCO3). Calcine to obtain lead sulfate and lead oxide, and then reducing to obtain metallic lead. Metal lead contacts with oxygen, water and carbon dioxide in the air, and its surface will be rapidly oxidized to form a protective film; When heated, lead can quickly combine with oxygen, sulfur and halogen; Lead has little effect on cold hydrochloric acid and cold sulfuric acid, but can react with hot or concentrated hydrochloric acid and sulfuric acid. Lead reacts with dilute nitric acid, but not with concentrated nitric acid; Lead will slowly dissolve in strong alkali solution. Lead is mainly used to manufacture lead storage batteries; Lead alloy can be used for casting type and welding; Lead is also used to make protective equipment for radioactive radiation and x-rays; Lead and its compounds are toxic to human body and can accumulate in human body. For example, Wei Boyang's "The Book of Changes" said: "Hu powder throws fire, and the color is still lead." According to today's chemical equation, the reaction of reducing Pb with Pb3O4+2C → 3PB+2CO2 ↑ is PbO+C == Pb+CO↑ PbO+CO == Pb+CO2. Experimental phenomenon: The generated gas can make the clear limewater turbid, and the yellow powder becomes a silvery white solid.

Of all the known toxic substances, lead is the most recorded in books. According to ancient books, it is very dangerous to transport drinking water with lead pipes. There are many ways for the public to be exposed to lead. In recent years, the public is mainly concerned about the lead content in petroleum products. Lead in pigments, especially some time-honored brands, has caused many deaths, so some countries have specially formulated environmental protection standards, stipulating that the lead content in pigments should be controlled within 600PPM. Some countries have not yet set standards, but when pigments with high lead content are sold in the market, they will put labels on them to warn users. There are also lead residues in food, or lead in the air pollutes food, or lead in canned skin pollutes canned food. Another important source of lead is lead pipes. Decades ago, lead pipes or lead-lined pipes were used to build houses, and natural refrigerators in summer were also lined with lead. Over the years, they have been banned and replaced by plastics or other materials. The safe limit of lead content in drinking water is 100 μ g/L, and the maximum acceptable level is 50 μ g/L. Later, it was further stipulated that the maximum acceptable concentration of lead in tap water is 50μ g/L (0.05mg/L). In addition, in order to study the effect of lead on human health, scientists began to detect the lead concentration in human blood samples as an early indicator of lead poisoning. The data show that if the drinking water is close to 50 μ g/L, the lead concentration in the patient's blood sample is above 30 μ g/L ... The requirements for baby care are more stringent, and the average blood lead concentration should not exceed10-15 μ g/L. In the water treatment process, the waterworks may add calcium and bicarbonate to keep the water alkaline, thus reducing the corrosion of water to water pipelines and bringing new water. But the corrosion problem is very complicated, and it can't be solved in this way. It should be overall purification, but it is expensive. Many chemicals may degrade into harmless final compounds after staying in the environment for a period of time, but lead cannot be degraded again, and once discharged into the environment, it will remain available for a long time. Lead has been listed as a strong pollutant because it exists in the environment for a long time and has strong potential toxicity to many biological tissues. At present, acute lead poisoning has been deeply studied, and its symptoms are: stomach pain, headache, trembling, nervousness, and even coma until death. At very low concentrations, the chronic long-term health effects of lead are as follows: affecting the brain and nervous system. Scientists have found that even if the lead concentration in blood samples of urban children is still acceptable, it still obviously affects children's intellectual development and abnormal behavior. Only by reducing the lead content in drinking water can we ensure that the total lead intake of people is reduced. The popularization and application of unleaded gasoline has made great contributions to reducing lead pollution in the environment, especially to reducing lead in atmospheric particles. Lead and particulate matter have drifted from cities to suburbs, from one province to another, and even abroad, affecting other regions and becoming public hazards in the world. Scientists drill icicles in the area where ice accumulates year after year on the iceberg in Greenland, North America. The age of the lower layer is long, and the age of the upper layer is near, so it is easy to determine the lead content of different layers of ice. The results show that before 1750, the lead content is only 20 μ g/ton; 50 μ g/ton in 1860; 1950 rose to 120 μ g/ton; 1965 greatly increased to 2 10 μ g/ton. With the development of modern industry, global pollution is becoming more and more serious.