Lead is a metal element that can be used as a material that resists sulfuric acid corrosion, anti-gamma rays, and batteries. Its alloys can be used for lead characters, bearings, cable sheathing, etc., and can also be used as sports equipment shot put. Lead can also refer to a writing instrument made of graphite or the like: a pencil. Plumbium (lead chalk and wood, the tools used by the ancients for writing, by means of collating).
Lead is a chemical element whose chemical symbol is Pb (Latin Plumbum) with an atomic number of 82. Lead is the highest atomic number among all stable chemical elements. The content of lead in the earth's crust is 0.0016%, and the main ore is galena. Lead is a kind of soft heavy metal, it is toxic, it is a weak metal with extension. The true color of lead is blue-white, and its surface is quickly covered with a dark gray oxide in the air. Lead is used as a building material, used in lead-acid batteries, used as bullets and shells, and solder, trophies, and some alloys also contain lead.
Lead is a bluish silver-white heavy metal that is toxic and is an extensible main group metal. Melting point 327.502 ° C, boiling point 1740 ° C, density 11.3437g/cm ^ 3, hardness 1.5, soft texture, tensile strength is small.
Lead is one of the earliest metals used by humans. In 3,000 BC, humans had smelted lead from ore. The content of lead in the earth's crust is 0.0016%, and the main ore is galena. There are four stable isotopes of lead in nature: lead 204, 206, 207, 208, and more than 20 radioactive isotopes.
Lead metal is affected by oxygen, water and carbon dioxide in the air, and its surface will quickly oxidize to form a protective film. Under heating, lead can be quickly combined with oxygen, sulfur, and halogen; lead and cold hydrochloric acid and cold sulfuric acid have almost no effect. , Can react with hot or concentrated hydrochloric acid, sulfuric acid; Lead reacts with dilute nitric acid, but does not react with concentrated nitric acid; Lead can slowly dissolve in strong alkaline solution.
Lead is not contained in the earth's crust. There is a very small amount of natural lead in nature. However, due to the accumulation of lead-containing minerals, the melting point is very low (328 °C), making lead used by people in ancient times.
Galena (PbS) has been the main source of lead for people today. In ancient times, people accidentally cast galena into a bonfire. It was first burned into an oxide and then reduced by carbon to form metallic lead.
In the British Museum, there is a statue of lead 3,000 BC discovered in the Abydos Mosque in Egypt. Among the materials obtained from the excavation of monuments in Ur city and other cities in Iraq, not only all kinds of metal objects belonging to the 4000 BC but also clay-plate documents recorded by the ancient Persian were used. These records show that a large amount of iron, copper, silver, and lead have been extracted from the ore in 2350 BC. From 1792 to 1750 BC, during the reign of Emperor Hammurabi of Babylon, large-scale lead production had already taken place. In China's Yin Dynasty tombs were also found in the lead made wine utensils, Jue, Yi and Ge.
The lead content in bronze ware from Shangyin to Han Dynasty in China has increased. The increase of lead in bronze has played an important role in improving the fluidity of liquid alloys, leaving the casting decorative.