From Planck’s thermo hypothesis to modern DFT — trace the 130-year journey that transformed our understanding of atoms, molecules, and chemical bonding.
1662
Boyle's LawExperiment
Robert Boyle
At fixed temperature, p ∝ 1/V — the first quantitative gas law.…
1787
Charles's LawExperiment
Jacques Charles
Gas volume rises linearly with temperature at fixed pressure.…
1824
Reflections on the Motive Power of FireMilestoneTheory
Sadi Carnot
Defined the ideal heat-engine cycle and its temperature-only efficiency limit — …
1840
Hess's LawTheory
Germain Hess
Reaction heats add along any path — enthalpy is a state function.…
1843
Mechanical Equivalent of HeatMilestoneExperiment
James Joule
Showed work and heat are interchangeable forms of energy.…
1850
First & Second Laws statedMilestoneTheory
Rudolf Clausius
Energy is conserved; heat does not spontaneously flow cold→hot.…
1850
Clausius–Clapeyron relationEquation
Clausius / Clapeyron
Quantified how vapour pressure varies with temperature.…
1865
Entropy namedMilestoneTheory
Rudolf Clausius
Coined 'entropy' and stated ΔS_univ ≥ 0 for the universe.…
1873
van der Waals EquationMilestoneEquation
J. D. van der Waals
Added molecular volume and attraction to the gas law; predicted the critical poi…
1876
Chemical thermodynamicsMilestoneTheory
J. Willard Gibbs
'On the Equilibrium of Heterogeneous Substances' — chemical potential, the phase…
1884
van't Hoff EquationEquation
Jacobus van't Hoff
Temperature dependence of the equilibrium constant (first Nobel in Chemistry, 19…
1888
Le Chatelier's PrincipleTheory
Henry Le Chatelier
Equilibria shift to oppose an imposed change in T, p, or concentration.…
1889
Nernst EquationMilestoneEquation
Walther Nernst
Linked cell potential to concentration (Nobel 1920).…
1877
Statistical entropy S = k ln WMilestoneTheory
Ludwig Boltzmann
Tied entropy to the number of microstates — the bridge to statistical mechanics.…
1906
Third Law of ThermodynamicsTheory
Walther Nernst
Entropy approaches a constant (zero for perfect crystals) as T → 0 K.…
1909
Enthalpy formalizedTheory
Heike Kamerlingh Onnes
Named the H = U + pV function central to constant-pressure chemistry.…
1923
Activities & non-idealityModel
Lewis & Randall
'Thermodynamics' textbook introduced fugacity and activity for real systems.…
1923
Debye–Hückel theoryModel
Debye & Hückel
Predicted activity coefficients of electrolyte solutions from electrostatics.…