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Advances in the atomic-molecular theory
The constitution of the atom
The dawn of the mole concept
First estimation of the molecular dimensions First determination of the molar gas constant R
First determinations of Planck (h), Boltzmann (KB), and Avogadro (NA) constants
The electron The proton The isotopes The neutron
Giuliano Moretti, CnS La Chimica nella Scuola, N.5, pp. 13-27, 2016
The H atom
Richter (1792) and Wallaston (1814)
Concept of chemical equivalencyEquivalent weights of acids and bases
Dalton (1803 - 1808)
“Atomic” (Equivalent)weights, rule of simplicity
Avogadro (1811)
Equal V equal number ofmolecules (p, T)
Dulong and Petit (1814)
In solid substancesCa ≈ 6 cal gram-atom-1 °C-1
Faraday (1834)
Laws of electrolysis
Cannizzaro (1858)
Avogadro’s principle and law of atoms(corrected atomic weights and formulas)
Mendeleev (1869)
The Periodic Table
Loschmidt (1865)
Kinetic theory of gases
Horstmann (1873)
P(V/n) = RT(V/n = molar volume)
van der Waals (1873)
[P+a/(V/n)2][(V/n)-b]=RT
Planck (1901)Black body radiation:h and KB then NA=KB/R(Idea of the quantum)
Einstein (1905)Brownian movement andother methods tocalculate NA (and ma(H))
Millikan (1909)Electron charge andFaraday’s constant:NA= F/e
Perrin (1909)NA by verification of the Einstein’sequation on the Brownian movementand other methods; book Les Atoms, 1913
Thomson (1896)Determination ofe/m(e) and e/ma(H)(ma(H) = 1700 m(e))
Rutherford (1908) and Moseley (1913)
Radioactivity and the conceptof atomic number
Soddy (1913) and Aston (1919)
Existence of isotopes formost of the elements
Bohr (1913)
The first quantummodel of the atom
Chadwick (1932)
The neutron and itsproperties (m(n) ≈ ma(H))