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960 terms · page 28 of 40
Overall Formation Constant
Chemical Equilibrium
Various
The equilibrium constant for the formation of a complex directly from the free metal ion and all its ligands.
β_n = K₁K₂ … K_n
Overall Order
Chemical Kinetics & Catalysis
Dimensionless
The sum of the individual orders with respect to every reactant appearing in the rate law.
n = m₁ + m₂ + …
Overpotential
Electrochemistry & Redox
V
The extra voltage beyond the theoretical value that must be applied before an electrode reaction proceeds at a useful rate.
η = E_applied − E_equilibrium
Oxidation
Electrochemistry & Redox
Dimensionless
The loss of electrons by a species, accompanied by an increase in its oxidation number.
M → Mⁿ⁺ + n e⁻
Oxidation Number
Electrochemistry & Redox
Dimensionless
The hypothetical charge an atom would carry if all its bonds were treated as fully ionic.
Σ oxidation numbers = overall charge
Oxidation Number Method
Stoichiometry & Chemical Reactions
Dimensionless
A technique for balancing redox equations by equating the total increase and decrease in oxidation numbers.
Σ increase = Σ decrease
Oxidation of Alcohols
Organic Chemistry
Dimensionless
The conversion of alcohols to carbonyl compounds or carboxylic acids by removal of hydrogen.
R–CH₂OH → RCHO → RCOOH
Oxidising Agent
Electrochemistry & Redox
V
A species that accepts electrons from another substance and is itself reduced in the process.
Oxoacid
Acids, Bases & Salts
Dimensionless
An acid in which the ionisable hydrogen is attached to oxygen, which in turn is bonded to a central atom.
HₙXOₘ
p-Block Elements
Atomic Structure & Periodicity
Dimensionless
The elements of groups 13 to 18, in which the outermost electrons progressively fill p orbitals.
ns² np¹⁻⁶
Packing Efficiency
States of Matter & Gas Laws
Dimensionless
The percentage of the total volume of a unit cell that is actually occupied by the constituent particles.
(volume of atoms / cell volume) × 100
Paramagnetism
Atomic Structure & Periodicity
BM
Weak attraction into a magnetic field, shown by substances containing one or more unpaired electrons.
μ = √(n(n+2)) BM
Parent and Daughter Nuclide
Nuclear & Radiochemistry
Dimensionless
The nuclide undergoing decay and the nuclide produced by that decay.
parent → daughter + radiation
Partial Pressure
States of Matter & Gas Laws
Pa
The pressure that one component of a gas mixture would exert if it alone occupied the whole volume.
p_i = x_i × p_total
Partition Coefficient
Chemical Equilibrium
Dimensionless
The equilibrium ratio of a solute's concentrations in two immiscible phases.
P = C₁ / C₂
Parts per Billion
Solutions & Colligative Properties
ppb
A concentration unit expressing one part of solute per thousand million parts of solution.
ppb = (m_solute / m_solution) × 10⁹
Parts per Million
Solutions & Colligative Properties
ppm
A concentration unit expressing one part of solute per million parts of solution by mass or volume.
ppm = (m_solute / m_solution) × 10⁶
Path Function
Thermochemistry & Thermodynamics
J
A quantity whose value depends on the specific route taken between two states.
δq, δw
Pauli Exclusion Principle
Atomic Structure & Periodicity
Dimensionless
The rule that no two electrons in an atom may have the same set of all four quantum numbers.
n, l, mₗ, mₛ must differ
Penetrating Power
Nuclear & Radiochemistry
mm
The depth to which a given type of radiation can travel into a material before being absorbed.
Peptide Bond
Biochemistry & Polymer Chemistry
Dimensionless
The amide linkage joining the carboxyl group of one amino acid to the amino group of the next.
–CO–NH–
Percentage Composition
Foundations of Chemistry
Dimensionless
The proportion by mass of each element in a compound, expressed as a percentage of the total mass.
% element = (n × A_r / M_r) × 100
Percentage Purity
Stoichiometry & Chemical Reactions
Dimensionless
The proportion of a sample that consists of the desired compound, expressed as a percentage of the total mass.
% purity = (mass pure / mass sample) × 100
Percentage Yield
Stoichiometry & Chemical Reactions
Dimensionless
The actual yield expressed as a percentage of the theoretical yield.
% yield = (actual / theoretical) × 100