Terms starting with U
7 terms
Ultraviolet–Visible Spectroscopy
Analytical Chemistry & Spectroscopy
nm
A technique that measures the absorption of ultraviolet and visible light by electronic transitions within molecules.
A = log(I₀/I)
Unimolecular Reaction
Chemical Kinetics & Catalysis
s⁻¹
An elementary step in which a single molecule rearranges or decomposes.
A → products, rate = k[A]
Unit Cell
States of Matter & Gas Laws
pm
The smallest repeating three-dimensional unit that, when stacked, reproduces the entire crystal lattice.
ρ = ZM / (a³N_A)
Units of the Equilibrium Constant
Chemical Equilibrium
Various
The dimensions carried by an equilibrium constant, determined by the change in the number of moles in the balanced equation.
units = (mol/L)^Δn
Unsaturated Fat
Biochemistry & Polymer Chemistry
Dimensionless
A fat containing one or more carbon–carbon double bonds in its fatty acid chains.
Unsaturated Solution
Solutions & Colligative Properties
mol/L
A solution containing less dissolved solute than it could hold at the given temperature.
Uranium–Lead Dating
Nuclear & Radiochemistry
years
A radiometric method that determines the age of very old rocks from the ratio of uranium to its lead decay products.
²³⁸U → ²⁰⁶Pb (4.47 Ga)