History of chemistry 1808, certain of his central ideas were soon adopted by most chemists. However, uncertainty persisted for half a century about how atomic theory was to be configured and applied to concrete situations; chemists in different countries developed several different incompatible atomistic systems. A paper that suggested a way out of this difficult situation was published as early as 1811 by the Italian physicist Amedeo Avogadro (1776-1856), who hypothesized that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules, from which it followed that relative molecular weights of any two gases are the same as
Kinetic theory of gases "K": This is a first non-trivial result of the kinetic theory because it relates pressure, a macroscopic property, to the (translational) kinetic energy of the molecules formula_12, which is a microscopic property. Rewriting the above result for the pressure as formula_13, we may combine it with the ideal gas law where formula_14 is the Boltzmann constant and formula_15 the absolute temperature defined by the ideal gas law, to obtain which leads to simplified expression of the average kinetic energy per molecule, The kinetic energy of the system is N times that of a molecule, namely formula_18. Then the temperature formula_15