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Showing 1681–1709 of 1709 reference entries

Measurement · PhysicsRadiant flux, intensity, irradiance, exitance and radiance

Optical power, directional power and surface densities are different quantities.

DefinitionMeasurement · PhysicsPhotometric weighting, lumen, candela, lux and luminance

Photometry weights radiation with a specified standard visual response.

DefinitionMeasurementWriting SI quantities and unit symbols

Symbol form, spacing and parentheses preserve the meaning of reported quantities.

DefinitionMeasurementGram prefixes and the kilogram exception

Mass prefixes attach to gram even though kilogram is the SI base unit.

DefinitionMeasurementRounding a result with its uncertainty

Report useful digits without treating extra digits as proof of accuracy.

MethodMeasurement · Physics · ChemistryCommon non-SI units and exact SI conversions

Common non-SI unit names require their correct SI scale factors.

DefinitionPhysics · ChemistryGas pressure as molecular momentum transfer

Molecular collisions link macroscopic pressure to random translational motion.

ModelChemistry · PhysicsOrdinary aggregate states and bulk behavior

Solid, liquid and gas describe bulk behavior rather than chemical identity.

ModelChemistryInferring empirical and molecular formulas from composition

Element mass ratios become atom ratios through molar masses, with uncertainty and sample identity retained.

MethodChemistryLewis structures and valence-electron accounting

A Lewis diagram accounts for bonding and nonbonding valence electrons in a specified connectivity.

MethodChemistryElectron-domain geometry and molecular shape

VSEPR distinguishes the arrangement of electron regions from the positions of atoms.

ModelChemistryElectronegativity, bond polarity and molecular polarity

Polar bonds can cancel in a molecule; molecular geometry matters.

ModelChemistrySolutions, solutes, solvents and solvation

Dissolution disperses specified molecular or ionic species in a solvent.

DefinitionChemistrySolubility, saturation and supersaturation

A saturation limit is an equilibrium property under specified conditions, not a synonym for concentration.

DefinitionChemistryFiltration separates retained solids from a fluid

Ordinary filtration separates undissolved particles; dissolved species can remain in the filtrate.

MethodChemistryDistillation and vapor–liquid composition

Distillation uses vapor–liquid partitioning and condensation, with a limit at an azeotrope.

MethodBiologyGene, allele, genotype and phenotype

Genomic sequence variants and observable traits describe different levels of biological information.

DefinitionBiology · ChemistryEnzyme substrates, active sites and induced fit

Substrate recognition and catalysis depend on a dynamic molecular environment.

ModelBiology · ChemistryMonomers, polymers and hydrolysis

Covalent subunit linkage and water-assisted cleavage explain biological polymer structure.

DefinitionBiology · ChemistrySugars, glycosidic linkages and polysaccharides

Sugar connectivity distinguishes energy-storage and structural polysaccharides.

DefinitionBiology · ChemistryFatty acids, storage lipids and membrane lipids

Lipids include several architectures rather than one repeating-monomer polymer class.

DefinitionBiology · ChemistryAmino-acid residues and peptide linkages

The peptide backbone and variable side chains are different parts of protein structure.

DefinitionBiology · ChemistryNucleotides and DNA/RNA backbone polarity

Bases carry sequence information on a chemically directional sugar–phosphate backbone.

DefinitionBiologyCell membrane, cell wall, cytosol and compartments

A cell's boundary, fluid interior and specialized structures have different roles.

DefinitionEarth & cosmos · MeasurementEarthquake location, source magnitude and local intensity

A source location or magnitude does not describe the shaking experienced at every site.

DefinitionEarth & cosmosAtmospheric composition and thermal layers

Composition and temperature structure describe different features of Earth's atmosphere.

ModelEarth & cosmosDrainage basins, outlets and water divides

Surface drainage boundaries depend on the chosen outlet and need not bound groundwater flow.

DefinitionEarth & cosmosThe celestial sphere and the observer's sky

A sky direction is an angular observation, not an object's three-dimensional distance.

ModelEarth & cosmos · MeasurementRight ascension, declination and reference epochs

Celestial angular coordinates require a declared reference system and date conventions.

Definition
ModelSource checked

Ordinary aggregate states and bulk behavior

ChemistryPhysics

Solid, liquid and gas describe bulk behavior rather than chemical identity.

Key knowledge

Under ordinary conditions, a solid maintains a characteristic shape and volume, a liquid flows and takes a container's shape while retaining a volume, and a gas expands through the available container volume. Solid and liquid volumes ordinarily respond much less to pressure than gas volumes. Plasma contains appreciable electrically charged particles with behavior distinct from an ordinary neutral gas. A flowing collection of solid grains remains granular solid material; a cloud contains liquid or solid particles dispersed in gas.

Conditions and scope

  • State the material, temperature and pressure; these are introductory bulk descriptions rather than exact rigidity or incompressibility laws.
  • A sample can contain multiple phases, and changing physical state does not by itself establish a change in chemical species.
Sources · 2

References

Sources retain their recorded scope. A source link alone does not establish verification of every statement.

  1. Chemistry 2e (2019), §1.2 Phases and classification of matterPaul Flowers, Klaus Theopold, Richard Langley and William R. Robinson · OpenStax/Rice UniversityTextbook chapteropenstax.orgRead source
  2. Physical Sciences 10: States of matterSiyavulaTextbook chaptersiyavula.comRead source

Evidence and review

Ordinary solid/liquid/gas bulk behavior, plasma and examples of granular or multiphase samples.

2026-10-10 · Independent Mathematics and Information editor (AI editorial/source review; not the Chemistry/Biology/Earth author). The specified introductory inventory has no unresolved demonstrated material gap after the changes and body-based reuse. Existing advanced references retain their historical scoped approvals. English-only reference prose and explicit Lithuanian-translation-pending status are preserved.

Foundational review

2026-10-10 · Independent AI editorial inspection of this new compact reference entry, its equations, applicability, sources and knowledge connections.

Sources from other places

Scope or convention differs

Ordinary solid, liquid and gas behaviour and phase changes.

These are familiar phases, not an exhaustive list of all states of matter.

Related reference entries

Explore relationships within this area of study and its connections to other areas.

Showing 1–3 of 3 relationships

Scientific relationships · 3 / 3

The relationship type describes the connection. Its linked statements, sources and conditions define the scope.

  1. Related to
    Relationship sources · 1

    Linked statements

    • Under ordinary conditions, a solid maintains a characteristic shape and volume, a liquid flows and takes a container's shape while retaining a volume, and a gas expands through the available container volume. Solid and liquid volumes ordinarily respond much less to pressure than gas volumes. Plasma contains appreciable electrically charged particles with behavior distinct from an ordinary neutral gas. A flowing collection of solid grains remains granular solid material; a cloud contains liquid or solid particles dispersed in gas.

    Physical state and spatial phase organization do not determine whether the material is an element, compound or mixture.

  2. Related to
    Relationship sources · 1

    Linked statements

    • Under ordinary conditions, a solid maintains a characteristic shape and volume, a liquid flows and takes a container's shape while retaining a volume, and a gas expands through the available container volume. Solid and liquid volumes ordinarily respond much less to pressure than gas volumes. Plasma contains appreciable electrically charged particles with behavior distinct from an ordinary neutral gas. A flowing collection of solid grains remains granular solid material; a cloud contains liquid or solid particles dispersed in gas.

    Temperature, pressure and composition determine the relevant stable phase or coexistence region; the bulk labels are not a phase diagram.

  3. Related to
    Relationship sources · 1

    Linked statements

    • Under ordinary conditions, a solid maintains a characteristic shape and volume, a liquid flows and takes a container's shape while retaining a volume, and a gas expands through the available container volume. Solid and liquid volumes ordinarily respond much less to pressure than gas volumes. Plasma contains appreciable electrically charged particles with behavior distinct from an ordinary neutral gas. A flowing collection of solid grains remains granular solid material; a cloud contains liquid or solid particles dispersed in gas.

    A physical-state change can retain species identity, while a chemical reaction changes the species represented.

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