Reference: Boorse 1966: The World of Atom
PART II – THE FOUNDATIONS OF ATOMIC CHEMISTRY
Chapter 10: The Birth of Atomic Theory (John Dalton 1766 – 1844)
Dalton was investigating why oxygen and nitrogen remained mixed in air and did not separate, when he accidentally discovered that oxygen and nitrogen combined in definite ratios. Dalton had a physical particle picture of gases, which led him to assume that a chemical reaction is only the combination of an atom of one substance with that of another. This led to the inference that the relative weights of the constituent atoms in compounds could be determined. This established the foundation of atomic chemistry.
Chapter 11: The Volume Combination of Gases (Joseph Louis Gay-Lussac 1778 – 1850)
Gay Lussac showed that if gases enter into chemical reactions, they do so in numerically simple volume ratios, and the volume of the products, if gaseous, may be expressed by simple integral numerical ratios to the volume of the original reactants. This is true for gases only, where the force of cohesion between atoms and molecules is minimum, and where most of the volume is due to the “atmosphere of heat” surrounding the nuclei. The volume ratio is, most likely, also the ratio of atoms and molecules that combine.
Chapter 12: Atoms and Molecules – Avogadro’s Law (Amedeo Avogadro 1776 – 1856)
Avogadro’s principle is that equal volumes of different gases at the same temperature and pressure contain the same number of molecules. By this principle, Avogadro correctly deduced the chemical formula for water, ammonia, nitrous oxide, nitric oxide and nitrogen dioxide. However, for the principle to be valid it was necessary to introduce a new hypothesis, namely, that the ultimate particles of many of the elementary gases such as hydrogen and nitrogen were molecules i.e., combinations of two, or sometimes more, atoms.
Chapter 13: The Search for Primordial Material (William Prout 1785 – 1850)
The notion that all matter is composed of the same primary substance and that when organized in different ways produces the various elements, occurs far back in antiquity. In Daltonian theory, atoms were distinguished by their different masses. Prout hypothesized that the atoms of all elements are simply combinations of hydrogen.
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MAIN POINTS
- Atoms of different substances combine in definite ratios.
- A chemical reaction is such combination of atoms of different substances.
- The force of cohesion between atoms and molecules is minimum in gaseous phase.
- Gases combine in numerically simple volume ratios.
- Equal volumes of different gases at the same temperature and pressure contain the same number of molecules.
- The ultimate particles of many elementary gases are combinations of two, or sometimes more, atoms.
- The atoms of all elements are simply combinations of hydrogen.
THEORY
The atom is a spinning nucleus surrounded by a vortex of energy substance. All its mass is concentrated in the nucleus of negligible volume. All its volume comprises of the energy vortex of negligible mass. All different atoms have masses that are multiples of the mass of hydrogen atom. These atoms combine in simple and definite ratios.
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