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LITHOEN

Chemical element

Hydrogen

Present in rocks chiefly as hydroxyl and water, whose presence lowers melting temperatures and changes how minerals deform.

Classification

atomic number
1
symbol
H
block
s

How this record is known

4
Settled consensus
Cited as the accepted position of the discipline.

4 of 4 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.

EstablishedFluids released from the subducting slab facilitate melting in the overlying mantle.

Fluids and melts liberated from subducting oceanic crust recycle lithophile elements back into the mantle wedge, facilitate melting, and ultimately lead to prolific subduction-zone arc volcanism.

  • precision note: This supersedes the Phase 2 hypothesis that water lowers the melting temperature of rock. The retrieved Tier A source states that liberated fluids facilitate melting; it does not state a melting-point depression as a general property of water in rock, and Lithoen therefore asserts the narrower statement the source supports.
  • method: Experimental petrology with direct laser-ablation ICP-MS analysis of fluids and melts equilibrated with basaltic eclogite.

Evidence support: Supported by the cited evidence one source

Evidence: Kessel 2005 Peer-reviewed

Established1 protons

Hydrogen has atomic number 1: its nucleus contains 1 protons, and that is what makes it hydrogen.

  • 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

Established1.00784–1.00811 u

The standard atomic weight of hydrogen is given as the interval [1.00784, 1.00811], 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.