Lead
Definition and meaning of Lead in chemistry.
Lead is a heavy, soft, malleable post-transition metal with the chemical symbol Pb and atomic number 82. It is a highly dense element that possesses a relatively low melting point compared to most transition metals.
In more detail
Lead is located in group 14 of the periodic table and is known for its bluish-white color that rapidly tarnishes to a dull, dark gray upon exposure to air. This metal exhibits exceptionally poor electrical conductivity and is highly resistant to corrosion, often forming a durable, protective oxide layer on its surface. Lead occurs naturally in the crust of the Earth, primarily heavily concentrated in the sulfide mineral galena (PbS), often discovered and mined alongside zinc, silver, and copper ores. Chemically, lead typically exhibits +2 and +4 oxidation states, with the +2 state being much more stable and prevalent in chemical compounds. Because it is highly toxic to humans and animals, causing severe neurological issues, its modern industrial applications have been significantly curtailed and regulated across the world, though it remains critically important in specific specialized fields.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | Pb |
| Atomic number | 82 |
| Atomic mass | 207.2 u |
| Category | Post Transition Metal |
| State at room temperature | Solid |
| Melting point | 327.46 °C (621.43 °F) |
| Boiling point | 1749 °C (3180 °F) |
| Year discovered | Known since antiquity |
Lead is widely used as the primary structural and chemical component in lead-acid batteries for automotive vehicles, and it serves as essential radiation shielding in medical x-ray rooms and nuclear facilities.
Frequently asked questions
Why is lead toxic to humans?
Lead interferes with various essential enzymes in the body and can cause severe neurological damage, particularly affecting the cognitive development of children.
What is the primary ore of lead?
The most common and economically important ore of lead is galena, which is composed of lead sulfide.