Lead
Definition and meaning of Lead in chemistry.
![Lead element card: symbol Pb, atomic number 82, atomic mass 207.2, electron configuration [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p², oxidation states +4 +2, Post-transition metal, group 14, period 6, solid at room temperature.](/assets/images/terms/lead-chemical-element.webp)
Lead is a heavy, soft, and easily shaped post-transition metal with the chemical symbol Pb. It has an atomic number of 82 and feels extremely dense for its size. Lead melts at a much lower temperature compared to most other common metals.
In more detail
Lead sits in group 14 of the periodic table as a heavy post-transition metal. A freshly cut piece of lead shows a shiny bluish-white color, but it quickly tarnishes in the air. This exposure creates a dull gray oxide layer that protects the metal from further corrosion.
Lead conducts electricity very poorly, which is unusual for a heavy metal. In nature, lead is found in the mineral galena, which consists of lead sulfide. Mining companies extract this mineral alongside other valuable metals like zinc and copper.
In compounds, lead typically has plus 2 and plus 4 oxidation states. The plus 2 state is much more stable than the plus 4 state. A common student misconception is that writing pencils contain lead, but they actually use non-toxic carbon graphite.
Lead is also highly malleable, which lets workers bend and shape it without heating it up first. Lead is a cumulative poison that is highly toxic to humans and animals. It mimics other essential minerals like calcium and iron to enter our cells.
Once inside, it blocks vital enzymes and causes permanent brain damage. Because of these health risks, governments now limit its use in household products.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | Pb |
| Atomic number | 82 |
| Atomic mass | 207.2 u |
| Category | Post-Transition-Metal |
| Melting point | 327.46 degrees Celsius |
| Year discovered | Known since antiquity |
Lead serves as the main active ingredient in lead-acid batteries for cars. It also acts as an excellent shield against dangerous high-energy radiation. Hospitals use thick lead sheets to protect doctors and patients from medical X-rays.
Frequently asked questions
Why do we call pencil cores lead if they are made of carbon?
Ancient Romans wrote with actual lead rods that left dark marks on paper. When people discovered graphite in England, they thought it was a form of lead and kept the name.
How does lead block harmful radiation like X-rays so effectively?
Lead has a high atomic number of 82 and a dense electron cloud. These traits let it absorb and scatter incoming radiation before the energy can pass through.
Which oxidation state of lead is most common in chemical compounds?
The plus 2 oxidation state is much more common and stable than the plus 4 state. The inert pair effect stabilizes the outer electrons and makes them harder to lose.
Related terms
Sources & references
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