CONSERVATION OF ATOMS
Atoms are not created or destroyed in chemical reactions.

CONSERVATION OF MASS (CHEMICAL REGIME)
Mass is conserved in chemical reactions within measurement precision.

CONSERVATION OF ELECTRIC CHARGE
Net electric charge remains constant in chemical reactions.

THERMODYNAMIC FEASIBILITY (GIBBS FREE ENERGY)
A reaction is spontaneous only if ΔG < 0 under given conditions.

CHEMICAL EQUILIBRIUM CONSTRAINT
For a given reaction and temperature, the equilibrium constant fixes the final composition.

ACTIVATION ENERGY BARRIER
Reaction rate is limited by activation energy and collision frequency.

PHASE DIAGRAM CONSTRAINTS
State of matter is bounded by temperature–pressure phase diagrams.

SOLUBILITY LIMIT
For given conditions, there is a maximum concentration of solute that can dissolve.

QUANTISED ELECTRON ENERGY LEVELS
Electrons occupy discrete energy levels in atoms and molecules.

VALENCE CONSTRAINT
Atoms bond according to allowed electron configurations.

PH STABILITY RANGE (AQUEOUS SYSTEMS)
Acidity and alkalinity are bounded by the autoionisation of water.

REACTION YIELD LIMIT
Chemical reactions do not achieve 100% conversion under all conditions due to equilibrium and competing processes.

CATALYTIC NEUTRALITY
Catalysts change reaction rate but do not change equilibrium position.