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Showing 61–90 of 1709 reference entries

Physics · MeasurementElectric current

Current measures charge crossing a chosen surface per unit time.

DefinitionPhysicsElectric field and force

An electric field assigns force per unit test charge.

DefinitionPhysicsMagnetic force on a moving charge

Magnetic force depends on charge motion relative to the field.

ModelPhysicsOhm's law and its domain

A linear current-voltage relation requires suitable conditions.

Empirical findingPhysicsFirst law of thermodynamics

Keep the heat and work sign convention explicit in an energy balance.

ModelPhysicsSecond law: isolated-system entropy

Apply entropy increase to the whole isolated system.

ModelPhysics · ChemistryIdeal-gas equation of state

A simple gas model relates pressure, amount, volume and temperature.

ModelPhysicsPhoton energy and frequency

One photon's energy is proportional to its frequency.

ModelPhysics · Mathematics & logicInvariant spacetime interval

Lorentz transformations preserve a combined space-time separation.

ModelPhysicsNewton's third law

Interaction forces act on different bodies in equal and opposite pairs.

ModelPhysicsAngular momentum and torque

Torque changes angular momentum about a specified origin.

ModelPhysicsHydrostatic pressure

Static fluid pressure rises with depth under gravity.

ModelPhysicsArchimedes' buoyancy principle

The hydrostatic upward force equals displaced-fluid weight.

ModelPhysicsMaxwell equations in free space

Four field equations connect electric and magnetic fields with charge and current.

ModelPhysicsSchrödinger time evolution

A quantum wavefunction evolves according to its Hamiltonian.

ModelPhysicsBorn position probability

A normalized wavefunction assigns probabilities to position intervals.

ModelPhysics · MeasurementElementary charge

The elementary charge has an exact SI numerical value.

DefinitionPhysics · MeasurementBoltzmann constant

The Boltzmann constant has an exact SI numerical value.

DefinitionMeasurement · Chemistry · PhysicsAvogadro constant

The mole is linked to a specified number of entities.

DefinitionMeasurement · PhysicsSI defining luminous efficacy

A specified frequency fixes the photometric SI reference.

DefinitionChemistryAtoms and elemental identity

The proton count of an atomic nucleus identifies its chemical element.

DefinitionChemistryIsotopes and mass number

Isotopes share a proton count but have different neutron counts.

DefinitionChemistryPeriodic organization of the elements

Atomic-number order reveals recurring patterns in electron structure and chemical properties.

ModelChemistryChemical bonds

Bonding describes interactions that bind atoms into molecules or extended structures.

DefinitionChemistry · MeasurementMole and amount of substance

The mole counts specified entities using the exact Avogadro constant.

DefinitionChemistryReaction stoichiometry

Balanced coefficients relate the amounts consumed and produced by a reaction.

MethodChemistryBalancing atoms and electric charge

A chemical equation must preserve each element's atom count and the total charge.

MethodChemistryDynamic chemical equilibrium

At equilibrium, opposing reactions continue without net composition change.

ModelChemistryBrønsted acids and bases

In the Brønsted description, an acid donates a proton and a base accepts it.

DefinitionChemistryGibbs energy and thermodynamic direction

Gibbs-energy change distinguishes thermodynamic favourability from reaction speed.

Model
MethodSource checked

Balancing atoms and electric charge

Chemistry

A chemical equation must preserve each element's atom count and the total charge.

Key knowledge

A balanced equation for an ordinary chemical reaction has equal numbers of atoms of each element and equal total electric charge on both sides. Balance the coefficients rather than changing a substance's formula; include electron transfer when balancing redox half-reactions.

Conditions and scope

  • Applies to chemical reactions, not nuclear transmutation.
  • Account for ions and any explicitly represented electrons when checking charge.
Sources · 4

References

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

  1. Chemistry 2e (2019), §4.1 Writing and balancing chemical equations: ionic equationsPaul Flowers, Klaus Theopold, Richard Langley and William R. Robinson · OpenStax/Rice UniversityTextbook chapteropenstax.orgRead source
  2. Chemistry 2e, 17.1 Oxidation Numbers and Redox Half-Reaction AccountingPaul Flowers, Klaus Theopold, Richard Langley and William R. Robinson — OpenStax, Rice UniversityTextbook chapteropenstax.orgRead source
  3. Siyavula2 sources
    1. Physical Sciences 10: Balancing equationsSiyavulaTextbook chaptersiyavula.comRead source
    2. Physical Sciences 12: Redox reactionsSiyavulaTextbook chaptersiyavula.comRead source

Evidence and review

Published atom-count checks and charge-balancing steps; balancing alone does not demonstrate that a reaction occurs.

2026-10-10 · English balancing requirements checked against sections 4.1 and 17.1; no experimental conservation test was recreated.

Foundational review

2026-10-10 · Fresh primary-source inspection of the complete compact record, including every statement, equation, quantity and material condition, followed by independent AI editorial review. This check does not certify all linked lessons or every passage of every cited publication.

Sources from other places

Agreement within this scope

Atom counts, coefficients and charge/electron balance.

Balance ordinary chemical atoms and charge together.

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. Related to
    Relationship sources · 2

    Linked statements

    • Stoichiometric coefficients in a balanced chemical equation specify ratios of reactant consumption and product formation. These particle-number ratios also give mole ratios, so a known reacting amount can be converted into another reacting or produced amount.
    • A balanced equation for an ordinary chemical reaction has equal numbers of atoms of each element and equal total electric charge on both sides. Balance the coefficients rather than changing a substance's formula; include electron transfer when balancing redox half-reactions.

    The amount-ratio method uses a balanced chemical equation.

  2. Related to
    Relationship sources · 1

    Linked statements

    • Quantitative aqueous speciation combines equilibrium relations with conservation of analytical amounts and electroneutrality. A monoprotic acid has an analytical balance cT=[HA]+[A⁻]; water and all dissolved ions must also satisfy a charge balance. These equations can be solved together rather than assuming one dissociation fraction for every concentration.

    Electroneutrality and analytical balances preserve charge and matter.

  3. Uses definition
    Relationship sources · 1

    Linked statements

    • Oxidation states assign electrons formally rather than measuring atomic partial charge. A pure element has oxidation state zero, a monatomic ion's value equals its charge, and the sum over atoms in a chemical species equals its total charge. Increasing an atom's oxidation state is oxidation; decreasing it is reduction. Coupled half-reaction accounting preserves both atoms and total charge.

    Half-reactions retain atom and charge conservation.

  4. Related to
    Relationship sources · 3

    Linked statements

    • For a balanced reaction and one selected desired product, theoretical atom economy is its stoichiometric product mass divided by total stoichiometric reactant mass. Process mass intensity instead divides measured total process input mass by isolated product mass; the E factor divides waste mass by product mass. With matching boundaries and complete input-to-product-plus-waste accounting, PMI=E+1. Neither ratio measures toxicity, energy demand or actual reaction yield by itself.

    The conditional input/product/waste identity follows mass accounting.

Entry detailsPermanent link to this entry ↗
Record identity
chem-reaction-conservation
Revision
core.1
Structured reference record
Essential core · first collection