Short Introduction on Lead

The atomic structure of lead

What is lead? 



  Lead is the 82nd element on the periodic table and is represented by the symbol Pb. It is a soft metal with a bright appearance that quickly turns a dull gray color when exposed to air. Lead is toxic to humans as it can damage the nervous system and cause brain damage. Lead accumulates in the body and after many years of exposure, damage would be done. Despite this fact, lead has many uses in a wide variety of industries.
 
  Due to its abundance, low cost and physical properties such as the low melting point, corrosion resistance, waterproof nature and malleability, lead and lead compounds have been utilized in a variety of products.
 

(i) Most common use(s)/applications of the metal and/or its compounds in our daily life.

Past

Cosmetics

  The ancient Egyptians used lead for cosmetic uses.  The lead-based substances in the cosmetics promoted the production of nitric oxide in their skin, which helped strengthen their immune systems against diseases.

Ancient Egyptians using lead based cosmetics

Warfare

  Long before bullets were invented, lead was being used in warfare. Chunks of lead were hurled from slings at the enemy, and molten lead was poured down from forts onto attacking troops.

Paint, plumbing pipes, fuel, and pesticides

  Lead exposure has caused lead to be removed from many products.  Lead was once commonly used in paint, plumbing pipes, fuel, and pesticides, in the past. Today, these products are being actively phased out and the lead has been replaced by less toxic substances.

Present

Automobile industries

  
  Lead acid batteries are most commonly used in the automobile industry as the standard battery.  Lead is mostly used as electrodes in these batteries.  The chemistry of lead-acid produces a reliable voltage and with various construction designs for grids of the lead and pastes/gels of the acid produces batteries that can deliver huge amounts of power for a short time starting gas engines or medium amounts for a longer time while not being deeply discharged for power storage.

diagram of a lead acid battery

 Radiation shield 
  
  Lead is used as a radiation shield (aprons containing lead are used to shield) commonly in x-ray machines and other areas of possible radiation encounters. It is highly effective in shielding subjects from gamma rays and x rays by deflecting these rays. This is due to lead’s properties of large atomic mass, with its relatively shorter bond lengths and atomic radius. Hence, lead has a high density, and at the same time able to accommodate large number of compacted electrons, which absorb and scatter the energy in the rays.

 

lead shielding

 

 

Uses on the compounds of lead

Lead(II) Chloride

  Lead (II) Chloride  is used in production of infrared transmitting glass, and ornamental glass known as aurene glass.  Aurene glass has an iridescent surface formed by spraying with PbCl2 and reheating under controlled conditions.

Aurene glass

Lead oxide

   Lead oxide, also known as litharge, is widely used in plates making for electric storage batteries. Lead oxide is also used in ceramic and glass industries. Lead oxide is contained in lead glass. The addition of lead oxide raises the refractive index of glass, thus changing the optical characteristics of glass. It also raises the density of glass due to its high atomic number and reduces the transmission of radiation.

Lead dioxide

  Lead dioxide is used in lead acid batteries. This is due to its anomalous metallic conductivity. The lead-acid battery stores and releases energy by shifting the equilibrium between metallic lead, lead dioxide, and lead(II) salts in sulfuric acid.

Lead telluride and lead selenide

  Lead telluride and lead selenide are lead-based semiconductors and they are used in photovoltaic (solar energy) cells and infrared detectors. Lead telluride is also a good thermoelectric material due to its low thermal conductivity.

Done by:
Yong Kit Yuan