Lead is a dense, soft, malleable post-transition metal. It is a poor conductor, highly corrosion-resistant, and toxic; common oxidation states are +2 and +4.
The electron configuration of lead is [Xe] 4f14 5d10 6s2 6p2. It belongs to Group 14 and shares similarities with carbon, silicon, and tin in its outermost p-electrons, allowing it to exhibit oxidation states of +2 and +4.
Lead prefers the +2 oxidation state due to the inert pair effect. The 6s electrons are strongly bound to the nucleus and resist participation in bonding. This makes the +2 oxidation state (Pb2+) more stable than the +4 state (Pb4+).
\(\mathrm{Pb^{4+} \rightarrow Pb^{2+} + 2e^-}\)
Some common lead compounds include:
Lead is toxic because it interferes with enzyme activity and replaces calcium and zinc ions in the body, disrupting nervous system function. Chronic exposure can cause anemia, neurological damage, and developmental disorders, especially in children.
Despite its toxicity, lead has several industrial uses:
However, many of these uses are now restricted due to health hazards.
Lead does not react readily with non-oxidizing acids due to the formation of a protective oxide film. However, it reacts with nitric acid (HNO3) to form lead(II) nitrate:
\(\mathrm{3\,Pb + 8\,HNO_3 \rightarrow 3\,Pb(NO_3)_2 + 2\,NO + 4\,H_2O}\)
Lead is used in lead-acid batteries because of its ability to undergo reversible oxidation and reduction between Pb and PbO2. These redox reactions generate electrical energy efficiently:
\(\mathrm{Pb + PbO_2 + 2\,H_2SO_4 \leftrightarrow 2\,PbSO_4 + 2\,H_2O}\)
This makes lead-acid batteries reliable for starting and backup power systems.
Lead is a dense, bluish-gray metal with a melting point of 327.5 °C and a boiling point of 1749 °C. It is malleable, ductile, and resists corrosion due to the formation of a protective oxide layer.
Lead is effective as a radiation shield because of its high atomic number and density. These properties enable it to absorb X-rays and gamma rays efficiently, making it ideal for use in X-ray rooms and nuclear facilities.
Yes, lead can form covalent compounds, particularly in the +4 oxidation state. Examples include lead tetraethyl (Pb(C2H5)4) and lead tetrachloride (PbCl4). However, these compounds are unstable and often decompose easily.
Lead pollution arises from mining, smelting, and old paints or pipes. It contaminates soil and water and accumulates in living organisms. Leaded petrol, once a major source, has been globally phased out due to its role in air pollution and public health issues.