Classification and General Appearance
Metallic Nature
Lead is classified as a heavy metal. It exhibits characteristic properties associated with metals, such as high density, malleability, and ductility, though its ductility is limited compared to some other metals.
Color and Luster
When freshly cut, lead displays a bright silvery-bluish white appearance. However, upon exposure to air, it rapidly tarnishes due to oxidation, forming a dull grey or grayish-white coating of lead oxide or basic lead carbonate. This tarnish layer is what is commonly observed.
Texture
Lead is notably soft. It can be easily scratched with a fingernail or cut with a knife. It possesses a smooth feel to the touch. Due to its high density, lead objects feel significantly heavy for their size.
State at Room Temperature and Key Thermal Properties
State of Matter
At standard room temperature (approximately 25°C), lead exists as a solid.
Melting Point
Lead has a relatively low melting point for a metal, which is approximately 327.5 degrees Celsius (°C). This property made it historically useful in applications requiring a low-temperature molten state, such as soldering.
Boiling Point
The boiling point of lead is considerably higher than its melting point, approximately 1749 degrees Celsius (°C).
Other Notable Physical Characteristics
Density
Lead is a very dense metal. Its density is approximately 11.34 grams per cubic centimetre (g/cm³). This high density contributes to its use in applications such as radiation shielding, found in facilities like medical imaging departments in hospitals across India, and as weights.
Malleability and Ductility
Lead is highly malleable, meaning it can be easily hammered or pressed into thin sheets without breaking. Its ductility, however, is moderate; it can be drawn into wires but not as finely or easily as some other metals like copper or gold. This malleability made it historically useful for plumbing (e.g., lead pipes) and roofing materials.
Electrical and Thermal Conductivity
Compared to other common metals like copper or aluminium, lead is a relatively poor conductor of electricity. Its electrical conductivity is about 8% of that of copper. Similarly, it is not an excellent conductor of heat. These properties, combined with its density and softness, contribute to its application in sound damping and vibration absorption.