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LITHOEN

Chemical element

Lead

The daughter of uranium and thorium decay, and therefore the element whose isotopic composition records the age of the material containing it.

Classification

atomic number
82
symbol
Pb
block
p

How this record is known

3
Settled consensus
Cited as the accepted position of the discipline.

3 of 3 claims on this page cite at least one registered source. Counts describe how each statement is known, not how likely it is to be true.

What Lithoen records

Each claim states how it is known and cites its evidence.

Established82 protons

Lead has atomic number 82: its nucleus contains 82 protons, and that is what makes it lead.

  • definition basis: Atomic number is definitional: an atom with a different proton count is a different element, whatever else it shares.

Evidence support: Supported by the cited evidence one source

Evidence: Commission on Isotopic Abundances and Atomic Weights (IUPAC) 2024 Primary authority

Established206.14–207.94 u

The standard atomic weight of lead is given as the interval [206.14, 207.94], because its isotopic composition varies measurably between normal materials.

  • definition basis: CIAAW Standard Atomic Weights 2024. An interval is not an uncertainty: it is the range the value genuinely takes across normal materials.
  • precision note: A standard atomic weight is a property of the element as found in normal materials, not the mass of any individual atom.

Evidence support: Supported by the cited evidence one source

Evidence: Commission on Isotopic Abundances and Atomic Weights (IUPAC) 2024 Primary authority

In the knowledge graph

Record last updated 2026-09-06. Corrections follow the published corrections policy; superseded claims are retained, never silently edited.