In a redox reaction, a species that loses electrons and is thereby oxidized.
Reduction
A reaction involving the net gain of electrons or, equivalently, a decrease in oxidation number.
Resonance
Delocalization of electrons within a compound that cannot be adequately represented by Lewis
structures.
s subshell
The subshell corresponding to the angular momentum quantum number l = 0, and containing one
spherical orbital; found in all energy levels.
Salt
An ionic substance, i.e., one consisting of anions and cations, but not hydrogen or hydroxide ions.
Any salt can be formed by the reaction of the appropriate acid and base, e.g., KBr from HBr and
KOH.
Saturated hydrocarbon
A hydrocarbon with only single bonds.
Saturated solution
A solution containing the maximum amount of solute that can be dissolved in a particular solvent at
a particular temperature.
Scintillation counter
An instrument used to measure radioactivity by the amount of fluorescence produced.
Second law of thermodynamics