Lead (Latin for plumbum) is a chemical element, a metal with atomic number 82. In its pure form, the substance has a silvery, slightly bluish hue.
Because lead is widespread, it is easy to get and process. This metal has been known to humanity since ancient times. It is known that people have been using lead since the 7th millennium BC. In ancient Egypt and later in ancient Rome, lead was mined and processed. Lead is quite soft and malleable, so even before smelting furnaces were invented, it was used to make metal objects. For example, the Romans made pipes from the lead for a network of water pipes.
In the Middle Ages, lead was used as a roofing material and to make seals. For a long time, people were unaware of the substance’s harm, so it was put in wine and used in construction. Even in the 20th century, lead was added to a printing ink and gasoline additives.
In nature, lead is most commonly found as compounds that makes up ores. The ores are mined, and then the pure substance is isolated industrially. The metal itself, as well as its compounds, has unique physical and chemical properties, which explain the wide use of lead in various industries.
It has the following properties:
- Very soft, a docile metal that can be cut with a knife;
- heavy, denser than iron;
- melts at relatively low temperatures (327 degrees Celsius);
- Oxidizes rapidly in the air. A piece of pure lead is always covered with a layer of oxide.
Is lead toxic?
Lead has one unpleasant feature: it itself and its compounds are toxic. Lead poisoning is chronic. For example, with constant intake into the body, the element accumulates in the bones and organs, causing the most serious disorders.
But for a long time, the volatile compound tetraethyl lead was used to improve gasoline, which caused environmental pollution in cities. Now, in civilized countries, the use of this additive is prohibited.
Where is lead used?
The toxicity of lead is well-known these days. Lead, as well as its compounds, can bring enormous benefits if used rationally and intelligently.
The efforts of scientists and developers are aimed at maximizing the useful properties of lead, reducing its danger to humans. It is used in a variety of industries, such as:
- In medicine and other fields where protection against radiation is needed. Lead does not transmit any radiation well, so it is used as protection. In particular, lead plates are sewn into aprons worn by patients for safety during radiographic examinations. The protective properties of lead are used in the nuclear industry, science, and the production of nuclear weapons;
- In the electrical industry. Lead is a little susceptible to corrosion – this property is actively used in electrical engineering. But the most widespread are lead batteries. By the way, they are equipped with lead plates immersed in an electrolyte. The galvanic process makes it possible to get an electric current sufficient to start a car engine. Incidentally, it is the battery industry that is the largest consumer of lead in the world. In addition, lead is used to protect cables, make cable cuttings, fuses, superconductors;
- In the military industry. It is used in the manufacture of bullets, shots, and ammunition. Lead nitrate is used in explosive mixtures and lead azide is used as a detonator;
- In the manufacture of dyes and construction mixtures. Lead whitewash, extremely common in the past, is now giving way to other paints. Lead is used in the production of putties, cement, and protective coatings for glass and ceramics.
By the way, precisely because of the toxicity of lead, the use of this metal is being restricted by replacing it with alternative materials. Much attention is being paid to the safety of lead-related production facilities, to the recycling of products containing this element, and to reducing human contact with lead parts and the release of the substance into the environment.