Lead
Atomic Data
| Atomic Number | 82 |
| Symbol | Pb |
| Atomic Weight | 207.2 u |
| Density (STP) | 11.34 g/cm³ |
| Melting Point | 327.46 °C (600.61 K) |
| Boiling Point | 1748.85 °C (2022 K) |
| Electronegativity | 2.33 (Pauling) |
| Electron Config. | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p2 |
| Oxidation States | +2, +4 |
| Phase at STP | Solid |
| Category | Post-Transition Metal |
| Period / Group | 6 / 14 |
| CAS Number | 7439-92-1 |
Electron Configuration
[Xe] 4f14 5d10 6s2 6p2
| Shell | n | Subshell | Electrons | Cumulative |
|---|---|---|---|---|
| K | 1 | 1s | 2 | 2 |
| L | 2 | 2s | 2 | 4 |
| L | 2 | 2p | 6 | 10 |
| M | 3 | 3s | 2 | 12 |
| M | 3 | 3p | 6 | 18 |
| M | 3 | 3d | 10 | 28 |
| N | 4 | 4s | 2 | 30 |
| N | 4 | 4p | 6 | 36 |
| N | 4 | 4d | 10 | 46 |
| N | 4 | 4f | 14 | 60 |
| O | 5 | 5s | 2 | 62 |
| O | 5 | 5p | 6 | 68 |
| O | 5 | 5d | 10 | 78 |
| P | 6 | 6s | 2 | 80 |
| P | 6 | 6p | 2 | 82 |
| Total | 82 | 82 | ||
Isotopes of Lead
Lead has four naturally occurring stable isotopes. The most abundant is ²⁰⁸Pb, comprising 52.4% of all naturally occurring Lead.
| Isotope | Symbol | Protons | Neutrons | Abundance | Stability |
|---|---|---|---|---|---|
| Lead-204 | ²⁰⁴Pb | 82 | 122 | 1.4 | Stable |
| Lead-206 | ²⁰⁶Pb | 82 | 124 | 24.1 | Stable |
| Lead-207 | ²⁰⁷Pb | 82 | 125 | 22.1 | Stable |
| Lead-208 | ²⁰⁸Pb | 82 | 126 | 52.4 | Stable |
Abundance & Occurrence
Lead is present in Earth's crust at approximately 14 ppm by mass and at approximately 0.6 ppm by mass throughout the universe.
Earth's Crust (ppm by mass)
Universe (ppm by mass)
Discovery & History
Read more about the discovery of the periodic table of elements →
Safety & Handling
- Lead neurotoxicity: no safe threshold: Lead is a cumulative neurotoxin; there is no known safe blood lead level, particularly in children, where exposure causes irreversible cognitive impairment and behavioural effects even at very low levels.
- Inhalation of lead dust and fumes: Lead dust from sanding, grinding, or cutting lead-containing surfaces (paint, cable sheathing, solder) and lead fumes from soldering are the primary occupational exposure routes; these require LEV, RPE, and regular blood lead monitoring.
- Lead paint in older buildings: Paint in buildings constructed before the 1970s often contains lead; renovation and refurbishment of such buildings requires specialist lead-safe work practices: never dry-sand or dry-scrape lead paint.
- Lead in water: Lead pipework and solder in older buildings can leach lead into drinking water; flush taps before use and consider pipe replacement if blood lead levels are elevated in household members.
- Environmental persistence: Lead is persistent in soils and sediments near smelters, firing ranges, and contaminated land; contaminated soil must be managed to prevent ingestion or dust inhalation by children in adjacent communities.
Lead in the Real World
Real-World Uses
- Lead-acid batteries: Lead-acid batteries remain the dominant rechargeable battery technology for vehicle starting, lighting, and ignition (SLI) and for uninterruptible power supplies (UPS), using lead dioxide cathodes and lead anodes in sulfuric acid electrolyte.
- Radiation shielding: Lead's high density (11.3 g/cm³) and high atomic number make it the standard shielding material for X-ray rooms, nuclear reactors, medical radioisotope production areas, and portable radiation source containers (pigs and casks).
- Lead crystal glassware: Lead oxide (24–32%) in crystal glass increases refractive index, dispersion, and softness, giving lead crystal its distinctive brilliance and ring; increasingly replaced by barium and zinc crystal due to environmental concerns.
- Cable sheathing and architecture: Extruded lead sheathing protects underground power and telephone cables from moisture and corrosion; lead sheet is used in roofing, gutters, flashings, and radiation-shielded doors.
- Soldering (historical): Tin-lead solders (60/40, 63/37) were the standard for electronic assembly for decades; now largely replaced by lead-free SAC alloys under the EU RoHS directive, though lead solder is still permitted in high-reliability military and aerospace applications.
- Shot and ammunition: Lead shot and rifle bullets exploit lead's high density and deformability; use in shotgun ammunition and fishing weights is increasingly restricted due to wildlife poisoning from ingestion, being replaced by steel, bismuth, and tungsten alternatives.
Downloadable Resources
Free periodic table reference sheets for classrooms, study sessions, and laboratory use.
Frequently Asked Questions
What is lead used for?
Lead's main current uses are in lead-acid batteries (the rechargeable batteries in every petrol and diesel vehicle), radiation shielding (lead aprons and sheets used in X-ray facilities and nuclear installations), and as ballast weight. Lead was historically used in plumbing (the word 'plumbing' comes from the Latin 'plumbum', lead's symbol Pb), in solder, in paint pigments (red lead, white lead), and as tetraethyl lead in petrol: all now banned or phased out in most countries due to toxicity.
Is lead toxic?
Yes, lead is a potent neurotoxin with no known safe level of exposure, particularly in children. Lead interferes with brain development, causing reduced IQ, attention disorders, and behavioural problems. Lead poisoning (plumbism) also causes anaemia, kidney damage, and in severe cases seizures and death. The phasing out of leaded petrol beginning in the 1970s–90s is credited with a significant reduction in blood lead levels and correlated with improved cognitive test scores and reduced crime rates in many countries.
How was lead discovered?
Lead is one of the oldest metals known to humanity, smelted from galena (PbS) as early as 6500 BCE in Anatolia. The Romans used lead extensively: in water pipes, cooking vessels, wine sweetener (lead acetate, 'sugar of lead'), and as a pewter-like alloy: and some historians debate whether chronic lead exposure affected Roman public health. The chemical symbol Pb comes from the Latin 'plumbum'.
How does lead-acid battery recycling work?
Lead-acid batteries are the most recycled consumer product in the world: over 95% of the lead in batteries is recovered in most developed countries. In recycling, batteries are shredded and separated: lead plates and grids are smelted and refined back into pure lead, acid is neutralised or reclaimed, and plastic cases are recycled. The closed-loop recycling system means that nearly all lead in new batteries comes from old ones, reducing the need for primary lead mining.