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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
DefinitionSource checked

Solutions, solutes, solvents and solvation

Chemistry

Dissolution disperses specified molecular or ionic species in a solvent.

Key knowledge

A solution is a homogeneous mixture at the specified scale and conditions. The solvent is the component chosen as the dissolving medium, often the major component; the dissolved components are solutes. Solvation describes interactions of solvent species with dissolved species. Dissolving sucrose disperses molecules, whereas dissolving an ionic salt can disperse its ions. Dissolution is therefore different from melting, and it need not form a new covalent substance or always release heat.

Conditions and scope

  • Specify the components, phase, temperature and pressure. Solutions can be solid, liquid or gas; not every mixture forms one homogeneous phase.
  • Dissolution, dissociation and chemical reaction can coexist in a particular system and must be distinguished by the actual species.
Sources · 2

References

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

  1. Chemistry 2e (2019), §11.1 The dissolution processPaul Flowers, Klaus Theopold, Richard Langley and William R. Robinson · OpenStax/Rice UniversityTextbook chapteropenstax.orgRead source
  2. Chemistry XII: SolutionsNCERTTextbook chapter · PDFncert.nic.inRead source

Evidence and review

Solution composition, molecular versus ionic dissolution and solvent–solute interactions with either sign of dissolution heat.

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

Homogeneous mixtures, solvent/solute roles and dissolution equilibrium.

This comparison covers mixtures and dissolution; microscopic solvation detail remains in the existing references.

  • NCERT

    • Chemistry XII: Solutions
      IndiaEnglish

      §1.1, printed pp1–2: solution, solute and solvent; §1.3.1, printed pp5–6: dissolution and saturation equilibrium; §1.5.2, printed p14: azeotropic composition

Related reference entries

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

Showing 1–4 of 4 relationships

Scientific relationships · 4 / 4

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

  1. Uses definition
    Relationship sources · 1

    Linked statements

    • A solution is a homogeneous mixture at the specified scale and conditions. The solvent is the component chosen as the dissolving medium, often the major component; the dissolved components are solutes. Solvation describes interactions of solvent species with dissolved species. Dissolving sucrose disperses molecules, whereas dissolving an ionic salt can disperse its ions. Dissolution is therefore different from melting, and it need not form a new covalent substance or always release heat.

    A solution is a homogeneous mixture and need not be a pure substance.

  2. Related to
    Relationship sources · 1

    Linked statements

    • A solution is a homogeneous mixture at the specified scale and conditions. The solvent is the component chosen as the dissolving medium, often the major component; the dissolved components are solutes. Solvation describes interactions of solvent species with dissolved species. Dissolving sucrose disperses molecules, whereas dissolving an ionic salt can disperse its ions. Dissolution is therefore different from melting, and it need not form a new covalent substance or always release heat.

    Molecular dissolution and ionic dissociation produce different dissolved species.

  3. Uses definition
    Relationship sources · 1

    Linked statements

    • Solubility specifies an equilibrium dissolved composition for a solute, solvent and relevant phase at stated conditions. Relative to that limit, an unsaturated solution contains less solute, a saturated solution is at the limit, and a supersaturated solution contains more and is outside stable equilibrium with the relevant solute phase. Supersaturation can persist until nucleation or another pathway permits separation. A concentrated solution can be unsaturated, and a dilute solution can be saturated.

    The saturation comparison concerns the specified dissolved solute, solvent and phase.

  4. Related to
    Relationship sources · 2

    Linked statements

    • In ordinary solid–liquid filtration, the mixture passes through a compatible porous medium. Retained solid material is the residue or filter cake; the liquid passing through is the filtrate. Retention depends on particle and pathway sizes and the filter's behavior. A dissolved solute can pass with the liquid, so clear filtrate is not proof of chemical purity or absence of dissolved impurities.

    Dissolved species can travel with the filtrate while suitable undissolved solid particles are retained.

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