What is Lead?
Group 14 (IVa) of the periodic table contains lead (Pb), a soft, silvery-white or greyish metal. Lead is a poor conductor of electricity and is very malleable, ductile, and dense. Lead, which has been known since antiquity and is considered the oldest of metals by alchemists, is extremely durable and highly corrosive, as shown by the continuing use of lead water pipes installed by the ancient Romans. Pb is an abbreviation of the Latin word plumbum, and it is the lead symbol, which means "lead."
The density of lead is 11.29 gm/cm3 and +4 and +2 are the lead oxidation states. Let us look at what is lead and more details of the lead - Pb from this article.
Lead Properties
Physical Properties of Lead
A few of the physical properties of lead are given below.
Atomic
A lead atom has 82 electrons in the \[\left[Xe\right]\]4f145d106s26p2 electron configuration. The total energy required to remove the two 6p electrons from lead's first and second ionisation energy is similar to that of tin, lead's upper carbon group neighbour. This is odd because ionisation energy tends to decrease as an element's outer electrons become farther from the nucleus and more sheltered by smaller orbitals as it moves down the group.
Bulk
The colour of pure lead is bright, silvery, and has a tinge of blue. When it comes into contact with damp air, it tarnishes and develops a dull appearance, the colour of which varies depending on prevailing conditions. High density, malleability, ductility, and corrosion resistance due to passivation are all properties of lead.
Isotopes
Natural lead is made up of four stable isotopes with mass numbers of 204, 206, 207, and 208, as well as traces of five short-lived radioisotopes. A large number of isotopes is consistent with the lead having an even atomic number. The nuclear shell model appropriately predicts an extremely stable nucleus for lead because it has a magic number of protons (82). Lead-208 has 126 neutrons, which is another special number that could explain why it is so stable.
Let us look at the chemical properties of lead here.
Chemical Properties of Lead
Let us look at a few of the lead chemical formulas here.
Lead Chemical Formula
Occurrence and Distribution
Early biblical accounts frequently mention lead (Pb). The Babylonians utilised the metal to record inscriptions on plates. It was used by the Romans for tablets, water pipes, coins, and even cooking utensils; indeed, lead poisoning was recognised in Augustus Caesar's time as a result of the last use. The compound known as the white lead was reportedly produced as a decorative pigment as early as 200 BCE. The late 1700s saw the exploitation of deposits in the Missouri-Kansas-Oklahoma region of the U.s., which led to modern advancements.
Lead is nearly as abundant as tin in the Earth's crust in terms of weight. In the universe, there are 0.47 lead atoms for every 106 silicon atoms. Caesium, praseodymium, hafnium, and tungsten all have a cosmic relative abundance that is comparable to caesium, praseodymium, hafnium, and tungsten.
Despite the fact that lead is not abundant, natural concentration processes have resulted in significant commercial deposits, particularly in the United States, but also in Canada, Australia, Spain, Germany, Africa, and South America. The western states and the Mississippi Valley in the United States have significant deposits.
Lead is present in various minerals but is rarely found free in nature, excluding sulphide, PbS (galena, or lead glance), which is the world's primary source of lead production. Anglesite (PbSO4) and cerussite both contain lead (PbCO3). In the early 20th century, the main producers of lead in concentrate were China, Australia, the United States, Peru, Mexico, and India.
Roasting the ore and subsequently smelting it in a blast furnace or direct smelting without roasting are two methods for extracting lead. Impurities in the lead bullion produced by either process are removed by further refining. Recycled scrap accounts for nearly half of all refined lead. 11.29 gram/cm3 is the density of lead. The lead symbol is Pb.
The lead periodic table position can be represented as follows.
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Uses of Lead
Let us look at the uses of lead.
There is only one known crystalline alteration with a close-packed metallic lattice. The ductility, ease of welding, low melting point, high density, and capacity to absorb gamma and X-radiation are all properties that add to the elemental application of lead. For elemental silver and gold, molten lead is an excellent solvent and collector. The poor tensile and fatigue strengths of lead, as well as its tendency to flow even when lightly loaded, limit its structural application of lead.
When lead is freshly cut, it oxidized to form quickly, forming a dull grey coating that protects the metal from further corrosion. This coating was once considered to be lead suboxide (Pb2O), but it is now known to be a mixture of lead and lead monoxide (PbO). Similarly, despite the fact that lead is soluble in dilute nitric acid, hydrochloric or sulfuric acids only attack it superficially due to the formation of insoluble chloride (PbCl2) or sulphate (PbSO4) coatings.
Because of its chemical resistance, lead is commonly used in roofing, as covers for subterranean or underwater electric wires, and as linings for water pipes, conduits, and structures for the transit and processing of corrosive substances.
Although hydrogen ions can oxidise elemental lead to the Pb2+ ion, lead is resistant to many acids due to the insolubility of most Pb2+ compounds. The formation of the soluble species of lead in the +2 oxidation state makes oxidation under alkaline conditions easier to achieve. In acidic solution, lead oxide (PbO2, with lead as the Pb4+ ion) is one of the most strong oxidising agents, although it is very weak in alkaline solution. The ease with which lead can be oxidised is helped by complex formation. Aqueous solutions containing lead hexafluoro silicate and hexafluoro silicic acid are best for electrodeposition of lead.
These are the few important uses of lead.
Important Facts About Lead
Let us look at some of the key facts of Lead (Pb) here.
The metal element is toxic to humans and would target vital internal organs, causing lead poisoning in a number of cases.
Organ and brain growth in early childhood is reported to be hampered by the metal.
Lead is one of a handful of elements that have been known to humans since the beginning of time; as a result, it was never properly discovered. Lead was considered one of the oldest metals by alchemists.
FAQs on Lead (Pb)
1. What is lead (Pb) and what are its key physical characteristics?
Lead (Pb) is a soft, dense, and highly malleable heavy metal belonging to Group 14 of the periodic table. Its key physical characteristics include a silvery-white or bluish-grey appearance when freshly cut, a low melting point, and high resistance to corrosion. Lead is known for its high density (11.29 g/cm³) but is a poor conductor of electricity.
2. Why is the chemical symbol for lead 'Pb'?
The chemical symbol for lead is Pb because it originates from its Latin name, 'plumbum'. The Romans extensively used lead for making water pipes, and the word 'plumbing' is derived from this Latin term.
3. What are the common oxidation states of lead, and why is the +2 state more stable?
Lead exhibits two primary oxidation states: +2 and +4. The +2 oxidation state is significantly more stable and common than the +4 state. This is due to a phenomenon known as the 'inert pair effect', where the two electrons in the outermost 6s orbital are reluctant to participate in chemical bonding, making the removal of only the two 6p electrons more favourable.
4. How does lead resist corrosion despite being a reactive metal?
When lead is exposed to air, it quickly forms a thin, non-reactive protective layer on its surface. This passivation layer, typically a mixture of lead oxide (PbO) and lead carbonate, is highly durable and insoluble. It shields the underlying metal from further oxidation and attack by many acids, such as sulfuric and hydrochloric acid, which form insoluble lead salts (PbSO₄ and PbCl₂) on its surface, preventing further reaction.
5. What are the most important industrial uses of lead?
Lead has several significant industrial applications due to its unique properties. The most important uses include:
- Lead-Acid Batteries: The majority of lead produced globally is used in rechargeable car batteries.
- Radiation Shielding: Its high density and atomic number make it excellent for blocking X-rays and gamma radiation in medical facilities and nuclear reactors.
- Alloys: It is used to make alloys like solder (with tin) and pewter.
- Roofing and Construction: Its malleability and corrosion resistance make it a durable material for roofing sheets and linings.
6. What is lead poisoning and why is it a major health concern?
Lead poisoning is a serious medical condition caused by the accumulation of lead in the body. Lead is a potent neurotoxin that can cause severe damage to the nervous system, brain, kidneys, and reproductive organs. It is particularly dangerous for children, as it can impair cognitive development, leading to learning disabilities and behavioural problems, even at very low levels of exposure.
7. Why is lead an effective material for shielding against radiation?
Lead is an excellent material for radiation shielding primarily due to two factors: its high density and its high atomic number (82). The dense arrangement of atoms and the large number of electrons in each lead atom provide a high probability of interacting with and absorbing high-energy photons like X-rays and gamma rays, effectively stopping them from passing through.
8. What are some important compounds of lead?
Some of the most important compounds of lead include Lead(II) oxide (PbO), also known as litharge, which is used in making glass and ceramics; Lead(IV) oxide (PbO₂), which is a strong oxidizing agent used as the cathode in lead-acid batteries; and Trilead tetroxide (Pb₃O₄), or red lead, used as a pigment and in anti-corrosion paints.
