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960 terms · page 5 of 40
Binding Energy per Nucleon
Nuclear & Radiochemistry
MeV/nucleon
The nuclear binding energy divided by the number of nucleons, measuring the stability of a nucleus.
BE/A
Biochemistry
Biochemistry & Polymer Chemistry
Dimensionless
The study of the chemical substances and processes that occur within living organisms.
Biodegradable Polymer
Biochemistry & Polymer Chemistry
Dimensionless
A polymer that can be broken down into simple substances by the action of microorganisms.
Biomolecule
Biochemistry & Polymer Chemistry
Dimensionless
An organic molecule produced by and essential to a living organism.
Blank
Analytical Chemistry & Spectroscopy
Various
A sample containing everything except the analyte, measured to correct for background signal.
Body-Centred Cubic
States of Matter & Gas Laws
Dimensionless
A cubic arrangement with particles at the eight corners plus one at the centre of the cell.
2 atoms per cell, 68% packing
Bohr Model
Atomic Structure & Periodicity
Dimensionless
The 1913 model in which electrons orbit the nucleus in fixed circular paths of quantised energy and angular momentum.
mvr = nh / 2π
Boiling Point
States of Matter & Gas Laws
°C
The temperature at which the vapour pressure of a liquid equals the external pressure acting on it.
p_vap = p_external
Boiling Point Elevation
Solutions & Colligative Properties
°C
The rise in a solvent's boiling point caused by the presence of a non-volatile solute.
ΔT_b = i K_b m
Bomb Calorimeter
Thermochemistry & Thermodynamics
J
A rigid sealed vessel used to measure the heat released by combustion at constant volume.
q_V = ΔU
Bond Angle
Chemical Bonding & Molecular Structure
degrees
The angle between two bonds that share a common atom.
Bond Dissociation Enthalpy
Thermochemistry & Thermodynamics
kJ/mol
The enthalpy change when one mole of a specific bond is broken homolytically in the gas phase.
A–B(g) → A·(g) + B·(g)
Bond Energy
Chemical Bonding & Molecular Structure
kJ/mol
The energy required to break one mole of a given bond homolytically in the gaseous state.
A–B(g) → A(g) + B(g)
Bond Length
Chemical Bonding & Molecular Structure
pm
The equilibrium distance between the nuclei of two bonded atoms.
d ≈ r₁ + r₂
Bond Order
Chemical Bonding & Molecular Structure
Dimensionless
The number of chemical bonds between a pair of atoms, or in molecular orbital terms half the difference between bonding and antibonding electrons.
BO = (N_b − N_a) / 2
Bond Polarity
Chemical Bonding & Molecular Structure
Dimensionless
The degree of unequal electron sharing in a covalent bond, arising from an electronegativity difference between the bonded atoms.
Δχ = |χ_A − χ_B|
Bonding Molecular Orbital
Chemical Bonding & Molecular Structure
Dimensionless
A molecular orbital lower in energy than the atomic orbitals from which it forms, whose occupation stabilises the molecule.
ψ = ψ_A + ψ_B
Bonding Pair
Chemical Bonding & Molecular Structure
Dimensionless
A pair of electrons shared between two atoms and responsible for holding them together.
Born–Haber Cycle
Chemical Bonding & Molecular Structure
kJ/mol
A thermochemical cycle applying Hess's law to determine the lattice energy of an ionic compound indirectly.
ΔH_f = ΔH_sub + IE + ½D + EA + U
Boyle's Law
States of Matter & Gas Laws
Pa·m³
At constant temperature, the volume of a fixed mass of gas is inversely proportional to its pressure.
p₁V₁ = p₂V₂
Breeder Reactor
Nuclear & Radiochemistry
Dimensionless
A reactor that produces more fissile material than it consumes by converting fertile nuclides.
²³⁸U + n → ²³⁹Pu
Brownian Motion
Solutions & Colligative Properties
m²/s
The continuous random zigzag movement of colloidal particles caused by uneven bombardment from surrounding molecules.
⟨x²⟩ = 2Dt
Brønsted–Lowry Theory
Acids, Bases & Salts
Dimensionless
The theory defining an acid as a proton donor and a base as a proton acceptor.
HA + B ⇌ A⁻ + BH⁺
Buffer Capacity
Acids, Bases & Salts
mol/L
The amount of strong acid or base a buffer can absorb before its pH changes appreciably.
β = dn / d(pH)