Lead Element Properties and Information
Lead Element Properties and Information
Lead is 82nd element on the periodic table. Elements are arranged in the periodic table on the basis of the atomic number. Atomic number is the number of protons in the nucleus of the atom. Lead has an atomic number of 82. It is located in the Group 14 and Period 6 of the periodic table of elements. It is denoted by the symbol ‘Pb’. The name is taken from its Anglo-Saxon word and the symbol from its Latin word.
Lead is one of those metals which have been used since ancient times all over the world. It has been known for 6000 years.
Lead rarely occurs in its free state, it is found on Earth in the form of chalcophile; meaning, combined with sulfur. The lead crystal abundance on Earth is 14 ppm.
Physical Properties
- Lead is a soft & malleable heavy metal which is denser than most common materials. Freshly cut lead is silver in appearance with a hint of blue.
- The atomic mass of lead is 207.2.
- The melting point of lead is 327°C.
- The boiling point of lead is 1755°C.
- The density of lead is 11340 in S.I. units at 20°C.
- The melting point of lead is lowest among the carbon group of elements.
Natural lead is composed of 4 stable isotopes; lead-204, lead-206, lead-207, and lead-208.
Chemical Properties
- Lead tarnishes very quickly when exposed to moist air.
- Lead reacts easily with fluorine at room temperature. But it has to be heated during its reaction with chlorine.
- Lead metal resists attacks by phosphoric and sulphuric acid, but it gets attacked by nitric and hydrochloric acid.
- Lead compounds display two main oxidation states: +4 and +2.
Methods of Production
- Two-stage process: Pre-processing of ores is done by grinding it and then subjecting it to dense-medium separation, froth-flotation, and drying. During the first stage, the ore is roasted to oxidise the lead sulfide. During the second stage, the lead oxide is reduced in a coke fired blast furnace to obtain the metal.
- Direct process: Pre-processing of ores is done by grinding it and then subjecting it to dense-medium separation, froth-flotation, and drying. The lead sulfide is melted and then oxidized in the furnace to form lead monoxide. The lead monoxide is reduced to lead metal by addition of carbon in the form of coke or coal gas.
Relevance in Chemical & Related Industries
- Colouring agents: Some lead based colouring compounds are used to impart yellow and red colour to glass and ceramic glazes.
- Copper alloy: Addition of lead to copper alloys improves its lubricating and machinability qualities.
Relevance in Other Industries
- Construction Industry: Lead is used in roofing materials, roof-parapets, flashing, cladding, gutter, and gutter-joints.
- Barrier: Lead has high density, formability, and atomic number due to which it can be applied to act as a barrier to sounds, vibrations, and even radiation. Also, lead does not have any resonant frequency.
- Lead-acid batteries: It is the largest known use of lead. The lead, lead-dioxide, and sulphuric acid provide a reliable source of voltage.
Health Effects on Exposure
- Physical: Rise in blood pressure, damage to kidney, damage to brain & nervous system, sperm damage, and miscarriage.
- Psychological: Diminishing of learning abilities, aggression & impulsive behaviour, and hyperactivity.
Effects on Surroundings
- Water poisoning: Some organisms like selfish and phytoplankton get poisoned by led even at small concentrations. Phytoplankton is an important source of oxygen production in the seas.
- Soil poisoning: The organisms within the soil get poisoned and lead can accumulate in the food chain.
References:
https://en.wikipedia.org/wiki/Lead
