Reed Relays and
Electronics India Limited
Manufacturer of Reed Switches, Reed Sensors and Reed-based products
Reed Relays and Electronics India Limited Incorporated in 1971


Lead is a chemical element with symbol Pb (Plumbum in Latin) and atomic number 82. Lead is a soft and malleable metal, which is regarded as a heavy metal and when ingested, is poisonous. This metal is banned by the RoHS directive.

Merriam-Webster Online Dictionary
lead (verb)
transitive verb
a) to guide on a way especially by going in advance
b) to direct on a course or in a direction
c) to serve as a channel for - a pipe leads water to the house
to go through - live lead a quiet life
a) (1) to direct the operations, activity, or performance of - lead an orchestra
(2) to have charge of - lead a campaign
(3) to ask (a witness) a question in a way that suggests what the answer should be to ask (a witness) a question - leading
b) (1) to go at the head of - lead a parade
(2) to be first in or among - lead the league
(3) to have a over - margin led his opponent
to bring to some conclusion or condition - led to believe otherwise
to begin play with - lead trumps
a) to aim in front of (a moving object) - lead a duck
intransitive verb
b) to pass a ball or puck just in front of (a moving teammate)
a) to guide someone or something along a way
b) to lie, run, or open in a specified place or direction - path leads uphill
c) to guide a dance partner through the steps of a dance
a) to be first
b) (1) - begin open
(2) to play the first card of a , round, or game - trick
to tend toward or have a result - study leading to a degree
to direct the first of a series of blows at an opponent in boxing guide
lead (noun)
a) (1) - leadership
(2) - example precedent
b) (1) position at the front - vanguard
(2) - initiative
(3) the act or privilege of playing first in a card game , also the card or suit played first
c) a or measure of advantage or superiority or position in advance - margin
one that as - leads
a) - lode
b) a channel of water especially through a field of ice
c) - indication clue
d) a role in a dramatic production - principal , also one who plays such a role
e) - leash
f) (1) an introductory section of a news story
(2) a news story of chief importance
an insulated electrical connected to an electrical device - conductor
the course of a rope from end to end
the amount of axial advance of a point accompanying a complete turn of a thread (as of a screw or worm)
a position taken by a base runner off a base toward the next
the first punch of a series or an exchange of punches in boxing
lead (adjective)
acting or serving as a lead or - (see lead) leader a lead article
lead (noun)
a bluish-white soft malleable plastic but inelastic heavy metallic element found mostly in combination and used especially in pipes, cable sheaths, batteries, solder, and shields against radioactivity - ductile see element table
a) a for sounding at sea - plummet
b) British a usually flat lead roof
c) lead framing for panes in windows
d) a thin strip of metal used to separate lines of in printing - type
a) a thin stick of marking substance (as graphite) in or for a pencil
b) - white lead
- bullets projectiles
- tetraethyl lead
lead (verb)
transitive verb
to cover, line, or weight with lead - (see lead)
to fix (window glass) in position with - leads
to put space between the lines of (typeset matter)
to treat or mix with lead or a lead compound - leaded gasoline
Lead (Wikipedia)
Lead,  82Pb
A small gray metal cube surrounded by three gray metal nuggets in front of a light gray background
General properties
Pronunciation /ˈlɛd/ (LED)
Appearance metallic gray
Standard atomic weight (Ar, std) 207.2(1)
Lead in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson


Atomic number (Z) 82
Group, period group 14 (carbon group), period 6
Block p-block
Element category   post-transition metal
Electron configuration [Xe] 4f14 5d10 6s2 6p2
Electrons per shell
2, 8, 18, 32, 18, 4
Physical properties
Phase (at STP) solid
Melting point 600.61 K ​(327.46 °C, ​621.43 °F)
Boiling point 2022 K ​(1749 °C, ​3180 °F)
Density (near r.t.) 11.34 g/cm3
when liquid (at m.p.) 10.66 g/cm3
Heat of fusion 4.77 kJ/mol
Heat of vaporization 179.5 kJ/mol
Molar heat capacity 26.650 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 978 1088 1229 1412 1660 2027
Atomic properties
Oxidation states 4, 3, 2, 1, −1, −2, −4 ​(an amphoteric oxide)
Electronegativity Pauling scale: 1.87 (+2)
Ionization energies
  • 1st: 715.6 kJ/mol
  • 2nd: 1450.5 kJ/mol
  • 3rd: 3081.5 kJ/mol
Atomic radius empirical: 175 pm
Covalent radius 146±5 pm
Van der Waals radius 202 pm
Color lines in a spectral range
Crystal structure face-centered cubic (fcc)
Face-centered cubic crystal structure for lead
Speed of sound thin rod 1190 m/s (at r.t.) (annealed)
Thermal expansion 28.9 µm/(m·K) (at 25 °C)
Thermal conductivity 35.3 W/(m·K)
Electrical resistivity 208 nΩ·m (at 20 °C)
Magnetic ordering diamagnetic
Magnetic susceptibility −23.0×10−6 cm3/mol (at 298 K)
Young's modulus 16 GPa
Shear modulus 5.6 GPa
Bulk modulus 46 GPa
Poisson ratio 0.44
Mohs hardness 1.5
Brinell hardness 38–50 MPa
CAS Number 7439-92-1
Discovery in the Middle East (7000 BCE)
Main isotopes of lead
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
204Pb 1.4% stable
206Pb 24.1% stable
207Pb 22.1% stable
208Pb 52.4% stable
Isotopic abundances vary greatly by sample
| references | in Wikidata

Lead is a chemical element that is assigned the symbol Pb (from the Latin plumbum) and the atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and has a relatively low melting point. When freshly cut, lead is bluish-white; it tarnishes to a dull gray color when exposed to air. Lead has the highest atomic number of any stable element and concludes three major decay chains of heavier elements.

Lead is a relatively unreactive post-transition metal. Its weak, metallic character is illustrated by its amphoteric nature; lead and lead oxides react with acids and bases, and it tends to form covalent bonds. Compounds of lead are usually found in the +2 oxidation state rather than the +4 state common with lighter members of the carbon group. Exceptions are mostly limited to organolead compounds. Like the lighter members of the group, lead tends to bond with itself; it can form chains, rings and polyhedral structures.

Lead is easily extracted from its ores; prehistoric people in Western Asia knew of it. Galena, a principal ore of lead, often bears silver, interest in which helped initiate widespread extraction and use of lead in ancient Rome. Lead production declined after the fall of Rome and did not reach comparable levels until the Industrial Revolution. In 2014, annual global production of lead was about ten million tonnes, over half of which was from recycling. Lead's high density, low melting point, ductility and relative inertness to oxidation make it useful. These properties, combined with its relative abundance and low cost, resulted in its extensive use in construction, plumbing, batteries, bullets and shot, weights, solders, pewters, fusible alloys, white paints, leaded gasoline, and radiation shielding.

In the late 19th century, lead's toxicity was recognized, and its use has since been phased out of many applications. Lead is a neurotoxin that accumulates in soft tissues and bones, damages the nervous system, and causes blood disorders. It is particularly problematic in children: even if blood levels are promptly normalized with treatment, permanent brain damage may persist.

« Back to Glossary Index