Chemistry terms starting with S

Self-Ionisation of Water Acids, Bases & Salts mol/L The reaction in which two water molecules transfer a proton to give a hydronium and a hydroxide ion. 2H₂O ⇌ H₃O⁺ + OH⁻

Semipermeable Membrane Solutions & Colligative Properties Dimensionless A barrier that allows solvent molecules to pass while blocking larger solute particles.

Sensitivity Analytical Chemistry & Spectroscopy Various The change in an instrument's response for a given change in analyte concentration. S = dSignal / dConcentration

Shielding Effect Atomic Structure & Periodicity Dimensionless The reduction in the nuclear attraction felt by an outer electron caused by repulsion from electrons in inner shells. Z_eff = Z − σ

SI Base Units Foundations of Chemistry Various The seven defined units of the International System from which every other measurement unit is derived.

Sievert Nuclear & Radiochemistry Sv The SI unit of equivalent dose, weighting absorbed dose by the biological damage the radiation type causes. H = D × w_R

Sigma Bond Chemical Bonding & Molecular Structure kJ/mol A covalent bond formed by the head-on overlap of atomic orbitals, with electron density concentrated along the internuclear axis.

Significant Figures Foundations of Chemistry Dimensionless The digits in a measured value that carry meaningful precision, comprising all certain digits plus one estimated digit.

Simple Cubic States of Matter & Gas Laws Dimensionless A crystal arrangement with particles only at the eight corners of a cubic unit cell. 1 atom per cell, 52% packing

Simultaneous Equilibria Chemical Equilibrium mol/L Several equilibria existing together in the same solution, all satisfied at once.

Single Displacement Reaction Stoichiometry & Chemical Reactions Dimensionless A reaction in which a more reactive element replaces a less reactive one from its compound. A + BC → AC + B

Slag Inorganic & Coordination Chemistry Dimensionless The molten by-product formed when a flux combines with the gangue during smelting.

Smelting Stoichiometry & Chemical Reactions °C The reduction of a metal oxide to the metal by heating with a reducing agent, usually carbon or carbon monoxide. MO + C → M + CO

SN1 Reaction Organic Chemistry s⁻¹ A two-step nucleophilic substitution proceeding through a carbocation intermediate. rate = k[substrate]

SN2 Reaction Organic Chemistry L/(mol·s) A single-step nucleophilic substitution in which bond formation and bond breaking occur simultaneously. rate = k[substrate][nucleophile]

Sol Solutions & Colligative Properties nm A colloidal system consisting of solid particles dispersed throughout a liquid medium.

Solid State States of Matter & Gas Laws Dimensionless The state of matter in which particles are held in fixed positions, giving a definite shape and volume.

Solubility Solutions & Colligative Properties g/100 g The maximum quantity of a solute that dissolves in a given amount of solvent at a specified temperature to give a saturated solution. S = g solute / 100 g solvent

Solubility and Ksp Relationship Chemical Equilibrium mol/L The mathematical link between molar solubility and the solubility product of a salt. Ksp = n^n m^m s^(m+n)

Solubility of Gases Solutions & Colligative Properties mol/L The amount of a gas that dissolves in a given volume of liquid at a stated temperature and partial pressure. S ∝ p, S decreases with T

Solubility Product Chemical Equilibrium Various The equilibrium constant for the dissolution of a sparingly soluble ionic solid into its constituent ions. Ksp = [A⁺]^m[B⁻]^n

Solubility Rules Stoichiometry & Chemical Reactions Dimensionless A set of empirical guidelines predicting whether an ionic compound will dissolve appreciably in water.

Solute Solutions & Colligative Properties mol The component of a solution present in the smaller amount, which is dispersed throughout the solvent.

Solution Solutions & Colligative Properties Dimensionless A homogeneous mixture in which one or more substances are dispersed uniformly at the molecular or ionic level in another.

Terms starting with S